This work was supported by National Science Foundation grant MCB-0951199, and in part by the NIH grant EY01910, California Institute of Regenerative Medicine grants RB1-01417 and by the Funda&#231;&#227;o para a Ci&#234;ncia e Tecnologia (FCT) grant SFRH/BD/87256/2012.

The authors declare that they have no competing financial interests.

الخطوات الأكثر أهمية لقياس النجاح في تدفقات أيون الخلية في الجسم الحي هي: الحد من الضوضاء، وتلفيق الصحيح للالميكروية ايون انتقائية والمرجعية القطب، وتحديد المواقع من العينة وكل من الأقطاب الكهربائية. من أجل الحد من الضوضاء...

<html> ويحيط كل الخلايا الحيوانية التي كتبها طبقة ثنائية الغشاء الدهني الذي يفصل السيتوبلازم من البيئة الخارجية. تحتفظ الخلية إمكانات غشاء الكهربائية، سلبية في الداخل، عن طريق النقل النشط لأيونات 1. غشاء المحتملة هي مصدر الطاقة المخزونة التي الخلية يمكن الاستفادة لتشغيل الأجهزة الجزيئية المختلفة في غشاء 2. الخلايا العصبية والخلايا منفعل أخرى لديها إمكانات غشاء كبيرة. افتتاح السريع للقنوات الصوديوم ينهار غشاء المحتملة (الاستقطاب) وتنتج إمكانات العمل التي يتم نقلها على طول العصبون 2. وبصرف النظر عن هذه التغييرات الكهربائية السريعة، والعديد من الأنسجة والأعضاء تولد والحفاظ على إمكانات كبيرة الكهربائية على المدى الطويل. على سبيل المثال، والجلد وظهائر القرنية توليد والحفاظ على الإمكانات عبر الظهارية والتيارات الكهربائية خارج الخلية من خلال ضخ الاتجاه من الأيونات (أساسا الصوديوم وكلوريد) 3. خيمة &quot;&gt; بينما قياسات الذاتية التيار الكهربائي خارج الخلية باستخدام مسبار تهتز 4-6 وقياسات غشاء أو عبر الظهارية إمكانات استخدام نظام مسرى مكروي 10/7 يتيح قياس المعلمات الكهربائية لأغشية الخلايا وطبقات الخلايا الظهارية، فإنها لا تعطي إشارة إلى الأنواع أيون المعنية. يمكن الميكروية مع حامل الأيون انتقائية قياس تركيز أيون معين في الحل. يمكن قياس التدرجات أيون أو التمويه مع اثنين أو أكثر من الأقطاب الكهربائية في مواقع مختلفة. ومع ذلك، فإن الانجراف الجهد لا يتجزأ من كل مسبار تكون مختلفة، مما تسبب قياسات غير دقيقة أو حتى الكشف عن الانحدار الذي لم يكن موجودا. A القطب واحد المستخدمة في وضع &quot;الرجوع إلى الذات&quot; حيث أنه يتحرك في التردد المنخفض بين نقطتين يحل هذه المشكلة. الآن تدفق الأيونات يمكن أن ينظر إليه على خلفية الانجراف إشارة بطيئة وثابتة نسبيا (انظر الشكل 3B). </P&gt; يستخدم نظام قياس حساسة ليثيوم-الميكروية الرجوع النفس ايون الانتقائي للكشف عن تدفقات خارج الخلية صغيرة من الأيونات قريبة من الأنسجة أو الخلايا وحيدة. ويتكون النظام من مكبر للصوت الذي يعالج الإشارة من مسرى مكروي والسائر المحركات الصغيرة والسائق للسيطرة على حركة مسرى مكروي. يتم توصيل مسرى مكروي ايون انتقائية والقطب المرجعية التي تغلق الدائرة إلى مكبر للصوت عن طريق headstage قبل مكبر للصوت (الشكل 1A). برامج الكمبيوتر يحدد معالم الحركة مسرى مكروي (تردد، وبعد المسافة) ويسجل أيضا إخراج مكبر للصوت. يتحكم المحرك السائر حركة مسرى مكروي عبر micropositioner ثلاثي الأبعاد. وقد تطورت A التردد المنخفض تهتز ايون انتقائية مسرى مكروي لأول مرة في 1990 لقياس تدفق الكالسيوم محددة 11. وكذلك الكالسيوم والكوكتيلات حامل الأيون الوصول تجاريا متاحة الآن لجعل ميكرoelectrodes حساسية للصوديوم وكلوريد البوتاسيوم والهيدروجين والمغنيسيوم، نترات الأمونيوم، الفلورايد، والليثيوم أو الزئبق. في الأساس، وايون انتقائية تقنية مسرى مكروي-الرجوع النفس تحويل نشاط أيون معين المذاب في محلول إلى الجهد الكهربائي، والتي يمكن أن تقاس الفولتميتر. كوكتيل حامل الأيون هو السائل إمتزاج (العضوية، محبة للدهون) المرحلة مع خصائص التبادل الأيوني. على حامل الأيون مجمعات انتقائي (الربط) أيونات معينة عكسية ونقل لهم بين محلول مائي الواردة في مسرى مكروي (بالكهرباء) ومحلول مائي التي يتم مغمورة مسرى مكروي (1D الشكل). هذا نقل أيون يؤدي إلى التوازن الكهروكيميائية ويتم قياس الاختلاف من الجهد الكهربائي بين مسرى مكروي والقطب المرجعية من قبل الفولتميتر. الجهد يتناسب مع لوغاريتم النشاط أيون معين وفقا لنرنست هquation السماح للحساب تركيز أيون (الشكل 2A و B). في الوقت الحاضر، العديد من النظم تسمح قياس تدفق الأيونات باستخدام مفهوم أو مبدأ مماثل. على سبيل المثال، القطب تقنية المسح الضوئي ايون انتقائية (SIET) 12،13 أو مسرى مكروي ايون الجريان تقدير (MIFE) تقنية وضعتها نيومان وShabala 14-16 متاحة تجاريا وتستخدم على نطاق واسع من قبل الأوساط البحثية من أجل تحديد أيون محدد الطلاءات التي تحدث في غشاء الخلايا والأنسجة عبر مجموعة متنوعة من الحيوانات والنباتات ونماذج خلية حية واحدة. وقد استخدمت الميكروية ايون انتقائية لقياس الهيدروجين والبوتاسيوم والكالسيوم تدفق عبر جذور النباتات 17، تدفق الكلوريد في الفئران الشرايين الدماغية 18 و 19 في أنابيب حبوب اللقاح، تدفق الهيدروجين في خلايا الشبكية تزلج 20، تدفق الكالسيوم في العظام بالنسبة للفئران 21، أيون مختلف الفيض في خيوط فطرية 22 و في صفي القرنية 23، وأخيرا تدفق الكالسيوم خلال الجرح خلية واحدة الشفاء 12،24. انظر أيضا الاستعراض التالي للحصول على معلومات مفصلة على الرجوع النفس الميكروية ايون الانتقائي 25. تتناول المقالة التالية بالتفصيل كيفية إعداد وتنفيذ قياس الذاتية تدفقات أيون الخلية باستخدام-الرجوع النفس تقنية مسرى مكروي ايون انتقائية على مستوى خلية واحدة.

<table border="0" cellpadding="0" cellspacing="0">
	<tbody>
		<tr>
			<td>IonAmp&#160;</td>
			<td>&#160;BioCurrents Research Center, Woods Hole, MA, USA</td>
			<td>none</td>
			<td>amplifier created by the BioCurrents Research Center, Woods Hole, MA, USA; Similar system can be purchased from &#8220;XBL function matters&#8221; (http://www.xuyue.org/) or from &#8220;YoungerUSA&#8221; (http://www.youngerusa.com/) or from Applicable Electronics(http://www.applicableelectronics.com/)</td>
		</tr>
		<tr>
			<td>IonAmp32&#160;</td>
			<td>&#160;BioCurrents Research Center, Woods Hole, MA, USA</td>
			<td>none</td>
			<td>software created by the BioCurrents Research Center, Woods Hole, MA, USA; Similar system can be purchased from &#8220;XBL function matters&#8221; (http://www.xuyue.org/) or from &#8220;YoungerUSA&#8221; (http://www.youngerusa.com/) or from Applicable Electronics(http://www.applicableelectronics.com/)</td>
		</tr>
		<tr>
			<td>Headstage pre-amplifier</td>
			<td>&#160;BioCurrents Research Center, Woods Hole, MA, USA</td>
			<td>INA116</td>
			<td>BSR Voltage Follower INA116, designed by the BioCurrents Research Center, Woods Hole, MA, USA; Similar system can be purchased from &#8220;XBL function matters&#8221; (http://www.xuyue.org/) or from &#8220;YoungerUSA&#8221; (http://www.youngerusa.com/) or from Applicable Electronics(http://www.applicableelectronics.com/)</td>
		</tr>
		<tr>
			<td>MicroStep Driver</td>
			<td>&#160;BioCurrents Research Center, Woods Hole, MA, USA</td>
			<td>none</td>
			<td>three MicroStep drivers are required for X, Y and Z-positioning; created by the BioCurrents Research Center, Woods Hole, MA, USA; Similar system can be purchased from &#8220;XBL function matters&#8221; (http://www.xuyue.org/) or from &#8220;YoungerUSA&#8221; (http://www.youngerusa.com/) or from Applicable Electronics(http://www.applicableelectronics.com/)</td>
		</tr>
		<tr>
			<td>Manual micropositioner&#160;&#160;</td>
			<td>World Precision Instruments&#160;</td>
			<td>Model KITE-R</td>
			<td>Similar system can be purchased from Applicable Electronics(http://www.applicableelectronics.com/)</td>
		</tr>
		<tr>
			<td>Magnetic stand&#160;&#160;&#160;</td>
			<td>World Precision Instruments</td>
			<td>Model M10</td>
			<td>Similar system can be purchased from Applicable Electronics(http://www.applicableelectronics.com/)</td>
		</tr>
		<tr>
			<td>Vibration isolation table&#160;&#160;</td>
			<td>Newport Inc.&#160;&#160;&#160;&#160;&#160;</td>
			<td>Model VW-3036-OPT-023040</td>
			<td>Similar system can be purchased from Applicable Electronics(http://www.applicableelectronics.com/)</td>
		</tr>
		<tr>
			<td>Part of three dimentional micropositioner: angle bracket, 90&#176;, slotted faces</td>
			<td>Newport Inc.&#160;&#160;&#160;&#160;&#160;</td>
			<td>Model 360-90</td>
			<td>Assemblage of the three dimantionnal micropositionner requires also Three electric rotary motors for X, Y, Z control, MPH-1 mounting arm with MCA-2 adjustable-angle post and Various Newport connectors and screws to bolt onto vibration table</td>
		</tr>
		<tr>
			<td>Part of three dimentional micropositioner: Peg-Joining Dovetail Stage 0.5 inch X Travel</td>
			<td>Newport Inc.&#160;&#160;&#160;&#160;&#160;</td>
			<td>460PD-X</td>
			<td>none</td>
		</tr>
		<tr>
			<td>Part of three dimentional micropositioner: Quick-Mount Linear Stage, 0.5 inch XY Travel</td>
			<td>Newport Inc.</td>
			<td>460A-XY</td>
			<td>none</td>
		</tr>
		<tr>
			<td>Kwik-Fil thin walled borosilicate glass capillaries without filament&#160;</td>
			<td>World Precision Instruments&#160;</td>
			<td>TW150-4</td>
			<td>none</td>
		</tr>
		<tr>
			<td>Electrode puller&#160;</td>
			<td>Narishige</td>
			<td>&#160;PC-10</td>
			<td>none</td>
		</tr>
		<tr>
			<td>Metal rack</td>
			<td>Made in-house</td>
			<td>none</td>
			<td>Metal electrode holder made in-house by drilling 2 mm wide holes half centimeter spaced in a 10cm by 15cm rectangular base of steel</td>
		</tr>
		<tr>
			<td>Oven</td>
			<td>QL</td>
			<td>Model 10 Lab Oven</td>
			<td>none</td>
		</tr>
		<tr>
			<td>Silanization solution I&#160;</td>
			<td>Sigma-Aldrich</td>
			<td>85126</td>
			<td>Hazardous, handle as recommended by provider&#160;</td>
		</tr>
		<tr>
			<td>Glass Petri dish; Pyrex</td>
			<td>Fisher Scientific</td>
			<td>316060</td>
			<td>none</td>
		</tr>
		<tr>
			<td>Electrode/micropipette storage jar</td>
			<td>World Precision Instruments&#160;</td>
			<td>E215</td>
			<td>none</td>
		</tr>
		<tr>
			<td>Glass dessicator</td>
			<td>Fisher Scientific</td>
			<td>08-595E</td>
			<td>Contains Drierite dessicant (W.A. Hammond Drierite Co. Ltd, Xenia, OH, USA). Place petroleum jelly on the seal to make it airtight.</td>
		</tr>
		<tr>
			<td>Plastic Pasteur pipette&#160;</td>
			<td>Fisher Scientific</td>
			<td>11597722</td>
			<td>none</td>
		</tr>
		<tr>
			<td>Bunsen burner</td>
			<td>Fisher Scientific</td>
			<td>S97329</td>
			<td>none</td>
		</tr>
		<tr>
			<td>Microscope slide</td>
			<td>Sigma-Aldrich</td>
			<td>S8902</td>
			<td>none</td>
		</tr>
		<tr>
			<td>Straight microelectrode holder</td>
			<td>Warner Instruments</td>
			<td>QSW-A15P</td>
			<td>with a gold 1 mm male connector and Ag/AgCl wire</td>
		</tr>
		<tr>
			<td>Straight microelectrode holder&#160;</td>
			<td>World Precision Instruments</td>
			<td>MEH3S</td>
			<td>with a AgCl(Ag+)pellet inside and a gold 2 mm male connector&#160;</td>
		</tr>
		<tr>
			<td>6 cm Petri dish</td>
			<td>VWR</td>
			<td>60872-306</td>
			<td>none</td>
		</tr>
		<tr>
			<td>Nitex mesh</td>
			<td>Dynamic Aqua-Supply Ltd.</td>
			<td>NTX750</td>
			<td>none</td>
		</tr>
		<tr>
			<td>Glue; Loctite epoxy</td>
			<td>VWR</td>
			<td>500043-451</td>
			<td>Mix glue and hardener in equal parts in a plastic weighing boat and mix thoroughly. Sets quickly but leave at RT for 24 h for full curing</td>
		</tr>
		<tr>
			<td>Deionized water&#160;</td>
			<td>Sigma-Aldrich</td>
			<td>99053</td>
			<td>none</td>
		</tr>
		<tr>
			<td>Sodium Chloride</td>
			<td>Sigma-Aldrich</td>
			<td>S7653</td>
			<td>none</td>
		</tr>
		<tr>
			<td>Potassium Chloride</td>
			<td>Sigma-Aldrich</td>
			<td>P9333</td>
			<td>none</td>
		</tr>
		<tr>
			<td>Calcium Chloride</td>
			<td>Sigma-Aldrich</td>
			<td>C1016</td>
			<td>none</td>
		</tr>
		<tr>
			<td>Magnesium Chloride</td>
			<td>Sigma-Aldrich</td>
			<td>M8266</td>
			<td>none</td>
		</tr>
		<tr>
			<td>Hepes</td>
			<td>Sigma-Aldrich</td>
			<td>H3375</td>
			<td>none</td>
		</tr>
		<tr>
			<td>Sodium Hydroxyde</td>
			<td>Sigma-Aldrich</td>
			<td>S8045</td>
			<td>none</td>
		</tr>
		<tr>
			<td>Potassium Acetate</td>
			<td>Sigma-Aldrich</td>
			<td>P1190</td>
			<td>none</td>
		</tr>
		<tr>
			<td>Agarose</td>
			<td>Sigma-Aldrich</td>
			<td>A9539</td>
			<td>none</td>
		</tr>
	</tbody>
</table>

measurement of extracellular ion fluxes using the ion-selective self-referencing microelectrode technique

يتم تضمين الخلايا من الحيوانات والنباتات والخلايا واحدة بحاجز يسمى غشاء الخلية التي تفصل بين السيتوبلازم من الخارج. طبقات الخلية مثل ظهائر أيضا تشكيل الحاجز الذي يفصل بين الداخل من الخارج أو حجرات مختلفة من الكائنات المتعددة الخلايا. ومن السمات الرئيسية لهذه الحواجز هي توزيع الفرق الأيونات عبر أغشية الخلايا أو طبقات الخلية. خاصيتين تسمح هذا التوزيع: 1) الأغشية وظهائر عرض النفاذية الانتقائية للأيونات محددة؛ 2) يتم نقل الأيونات خلال مضخات عبر أغشية الخلايا وطبقات الخلية. هذه الخصائص تلعب دورا حاسما في الحفاظ على وظائف الأعضاء والأنسجة بمثابة إشارات العظة بعد الضرر، خلال إصلاح، أو في ظل حالة المرضية. إلى الرجوع النفس مسرى مكروي ايون الانتقائي يسمح قياسات لتدفقات معينة من أيونات مثل الكالسيوم والبوتاسيوم أو الصوديوم عند مستويات الخلايا والأنسجة واحدة. يحتوي على مسرى مكروي كوكتيل حامل الأيون الذي هوقابلة للاختراق بشكل انتقائي إلى أيون معين. الحل ملء داخلي يحتوي على تركيز مجموعة من الأيونات في المصالح. يتم تحديد الجهد الكهربائي من مسرى مكروي من التركيز الخارجي للأيون. كما يختلف تركيز أيون، وإمكانات مسرى مكروي التغييرات بوصفها وظيفة من سجل النشاط أيون. عندما انتقلت ذهابا وإيابا بالقرب من مصدر أو بالوعة للأيون (أي في التدرج تركيز بسبب تدفق أيون) إمكانية مسرى مكروي يتقلب في اتساع يتناسب مع تدفق أيون / التدرج. مكبر للصوت تضخيم الإشارة مسرى مكروي ويتم تسجيل الإخراج على جهاز الكمبيوتر. ومن ثم يمكن حساب تدفق الأيونات بالقانون فيك من نشر باستخدام تذبذب القطب المحتملين، ورحلة من مسرى مكروي، وغيرها من المعالم مثل حركة الايونات معين. في هذه الورقة، ونحن تصف بالتفصيل منهجية لقياس تدفقات أيون الخلية باستخدام-الرجوع النفس مسرى مكروي لايون انتقائيةد تقديم بعض النتائج التمثيلية.

لقد أظهرنا سابقا أن تدفق الكالسيوم يظهر بعد خلية واحدة اصابة 24 اخرين. لذا سألنا عما إذا تدفقات ايون أخرى تحدث عند إصابة خلية واحدة. استخدمنا X. المورق البويضة، وهذا نموذج راسخة لخلية واحدة التئام الجروح 30-34 وتسجيل الكهربية 24،35-39. ومن المثير للاهت...

Watch this Scientific Journal Video about Measurement of Extracellular Ion Fluxes Using the Ion-selective Self-referencing Microelectrode Technique at JoVE.com

Measurement of Extracellular Ion Fluxes Using the Ion-selective Self-referencing Microelectrode Technique

Transporters in cell membranes allow differential segregation of ions across cell membranes or cell layers and play crucial roles during tissue physiology, repair and pathology. We describe the ion-selective self-referencing microelectrode that allows the measurement of specific ion fluxes at single cells and tissues in vivo.

قياس خارج الخلية ايون تدفقاتها باستخدام ايون انتقائية مسرى مكروي تقنية الرجوع الذاتي

Cells from animals, plants and single cells are enclosed by a barrier called the cell membrane that separates the cytoplasm from the outside. Cell layers ...

measurement-extracellular-ion-fluxes-using-ion-selective-self

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JoVE Journal

Biology

13.9K Views.  University of California, Davis. Transporters in cell membranes allow differential segregation of ions across cell membranes or cell layers and play crucial roles during tissue physiology, repair and pathology. We describe the ion-selective self-referencing microelectrode that allows the measurement of specific ion fluxes at single cells and tissues in vivo.

Video: Measurement of Extracellular Ion Fluxes Using the Ion-selective Self-referencing Microelectrode Technique

MALDI Sample Preparation: the Ultra Thin Layer Method

This video demonstrates the preparation of an ultra-thin matrix/analyte layer for analyzing peptides and proteins by Matrix-Assisted Laser Desorption Ionization Mass Spectrometry (MALDI-MS) 1,2. The ultra-thin layer method involves the production of a substrate layer of matrix crystals (alpha-cyano-4-hydroxycinnamic acid) on the sample plate, which serves as a seeding ground for subsequent crystallization of a matrix/analyte mixture. Advantages of the ultra-thin layer method over other sample deposition approaches (e.g. dried droplet) are that it provides (i) greater tolerance to impurities such as salts and detergents, (ii) better resolution, and (iii) higher spatial uniformity. This method is especially useful for the accurate mass determination of proteins. The protocol was initially developed and optimized for the analysis of membrane proteins and used to successfully analyze ion channels, metabolite transporters, and receptors, containing between 2 and 12 transmembrane domains 2. Since the original publication, it has also shown to be equally useful for the analysis of soluble proteins. Indeed, we have used it for a large number of proteins having a wide range of properties, including those with molecular masses as high as 380 kDa 3. It is currently our method of choice for the molecular mass analysis of all proteins. The described procedure consistently produces high-quality spectra, and it is sensitive, robust, and easy to implement.

This video demonstrates the preparation of an ultra-thin matrix/analyte layer for analyzing peptides and proteins by Matrix-Assisted Laser Desorption Ionization Mass Spectrometry (MALDI-MS).

MALDI تحضير العينة : الترا أسلوب طبقة رقيقة

This video demonstrates the preparation of an ultra-thin matrix/analyte layer for analyzing peptides and proteins by Matrix-Assisted Laser Desorption ...

Recapitulation of an Ion Channel IV Curve Using Frequency Components

INTRODUCTION: Presently, there are no established methods to measure multiple ion channel types simultaneously and decompose the measured current into portions attributable to each channel type. This study demonstrates how impedance spectroscopy may be used to identify specific frequencies that highly correlate with the steady state current amplitude measured during voltage clamp experiments. The method involves inserting a noise function containing specific frequencies into the voltage step protocol. In the work presented, a model cell is used to demonstrate that no high correlations are introduced by the voltage clamp circuitry, and also that the noise function itself does not introduce any high correlations when no ion channels are present. This validation is necessary before the technique can be applied to preparations containing ion channels. The purpose of the protocol presented is to demonstrate how to characterize the frequency response of a single ion channel type to a noise function. Once specific frequencies have been identified in an individual channel type, they can be used to reproduce the steady state current voltage (IV) curve. Frequencies that highly correlate with one channel type and minimally correlate with other channel types may then be used to estimate the current contribution of multiple channel types measured simultaneously.
METHODS: Voltage clamp measurements were performed on a model cell using a standard voltage step protocol (-150 to +50 mV, 5mV steps). Noise functions containing equal magnitudes of 1-15 kHz frequencies (zero to peak amplitudes: 50 or 100mV) were inserted into each voltage step. The real component of the Fast Fourier transform (FFT) of the output signal was calculated with and without noise for each step potential. The magnitude of each frequency as a function of voltage step was correlated with the current amplitude at the corresponding voltages.
RESULTS AND CONCLUSIONS: In the absence of noise (control), magnitudes of all frequencies except the DC component correlated poorly (|R|&lt;0.5) with the IV curve, whereas the DC component had a correlation coefficient greater than 0.999 in all measurements. The quality of correlation between individual frequencies and the IV curve did not change when a noise function was added to the voltage step protocol. Likewise, increasing the amplitude of the noise function also did not increase the correlation. Control measurements demonstrate that the voltage clamp circuitry by itself does not cause any frequencies above 0 Hz to highly correlate with the steady-state IV curve. Likewise, measurements in the presence of the noise function demonstrate that the noise function does not cause any frequencies above 0 Hz to correlate with the steady-state IV curve when no ion channels are present. Based on this verification, the method can now be applied to preparations containing a single ion channel type with the intent of identifying frequencies whose amplitudes correlate specifically with that channel type.

There are technical obstacles to measuring current flux through multiple ion channels simultaneously, and later discerning what portion of the transmembrane current is due to each channel type. To address this need, this method presents a way to generate the IV curve of individual channel types using specific frequency components.

خلاصة من المنحنى الرابع ايون القناة باستخدام مكونات التردد

INTRODUCTION: Presently, there are no established methods to measure multiple ion channel types simultaneously and decompose the measured current into ...

Measuring Fast Calcium Fluxes in Cardiomyocytes

Cardiomyocytes have multiple Ca2+ fluxes of varying duration that work together to optimize function 1,2. Changes in Ca2+ activity in response to extracellular agents is predominantly regulated by the phospholipase C&beta;- G&alpha;q pathway localized on the plasma membrane which is stimulated by agents such as acetylcholine 3,4. We have recently found that plasma membrane protein domains called caveolae5,6 can entrap activated G&alpha;q 7. This entrapment has the effect of stabilizing the activated state of G&alpha;q and resulting in prolonged Ca2+ signals in cardiomyocytes and other cell types8. We uncovered this surprising result by measuring dynamic calcium responses on a fast scale in living cardiomyocytes. Briefly, cells are loaded with a fluorescent Ca2+ indicator. In our studies, we used Ca2+ Green (Invitrogen, Inc.) which exhibits an increase in fluorescence emission intensity upon binding of calcium ions. The fluorescence intensity is then recorded for using a line-scan mode of a laser scanning confocal microscope. This method allows rapid acquisition of the time course of fluorescence intensity in pixels along a selected line, producing several hundreds of time traces on the microsecond time scale. These very fast traces are transferred into excel and then into Sigmaplot for analysis, and are compared to traces obtained for electronic noise, free dye, and other controls. To dissect Ca2+ responses of different flux rates, we performed a histogram analysis that binned pixel intensities with time. Binning allows us to group over 500 traces of scans and visualize the compiled results spatially and temporally on a single plot. Thus, the slow Ca2+ waves that are difficult to discern when the scans are overlaid due to different peak placement and noise, can be readily seen in the binned histograms. Very fast fluxes in the time scale of the measurement show a narrow distribution of intensities in the very short time bins whereas longer Ca2+ waves show binned data with a broad distribution over longer time bins. These different time distributions allow us to dissect the timing of Ca2+fluxes in the cells, and to determine their impact on various cellular events.

We present a method to isolate rapid (microsecond) calcium events from slower fluxes in living cells using laser scanning confocal microscopy. The method measures fluorescence intensity fluctuations of calcium indicators by recording line scans of several hundred pixels in a cell. Histogram analysis allows us to isolate the time scales of different calcium fluxes.

قياس الكالسيوم السريع في تدفقاتها العضلية

Cardiomyocytes have multiple Ca2+ fluxes of varying duration that work together to optimize function 1,2. Changes in Ca2+ activity in response to ...

Quantitative Measurement of Invadopodia-mediated Extracellular Matrix Proteolysis in Single and Multicellular Contexts

Cellular invasion into local tissues is a process important in development and homeostasis. Malregulated invasion and subsequent cell movement is characteristic of multiple pathological processes, including inflammation, cardiovascular disease and tumor cell metastasis1. Focalized proteolytic degradation of extracellular matrix (ECM) components in the epithelial or endothelial basement membrane is a critical step in initiating cellular invasion. In tumor cells, extensive in vitro analysis has determined that ECM degradation is accomplished by ventral actin-rich membrane protrusive structures termed invadopodia2,3. Invadopodia form in close apposition to the ECM, where they moderate ECM breakdown through the action of matrix metalloproteinases (MMPs). The ability of tumor cells to form invadopodia directly correlates with the ability to invade into local stroma and associated vascular components3. 
Visualization of invadopodia-mediated ECM degradation of cells by fluorescent microscopy using dye-labeled matrix proteins coated onto glass coverslips has emerged as the most prevalent technique for evaluating the degree of matrix proteolysis and cellular invasive potential4,5. Here we describe a version of the standard method for generating fluorescently-labeled glass coverslips utilizing a commercially available Oregon Green-488 gelatin conjugate. This method is easily scaled to rapidly produce large numbers of coated coverslips. We show some of the common microscopic artifacts that are often encountered during this procedure and how these can be avoided. Finally, we describe standardized methods using readily available computer software to allow quantification of labeled gelatin matrix degradation mediated by individual cells and by entire cellular populations. The described procedures provide the ability to accurately and reproducibly monitor invadopodia activity, and can also serve as a platform for evaluating the efficacy of modulating protein expression or testing of anti-invasive compounds on extracellular matrix degradation in single and multicellular settings.

We describe the prototypical method for producing microscope coverslips coated with fluorescent gelatin for visualizing invadopodia-mediated matrix degradation. Computational techniques using available software are presented for quantifying the resultant levels of matrix proteolysis by single cells within a mixed population and for multicellular groups encompassing entire microscopic fields.

قياس كمية Invadopodia بوساطة التحلل البروتيني المصفوفة خارج الخلية في سياقات متعددة الخلايا واحدة و

Cellular invasion into local tissues is a process important in development and homeostasis.  Malregulated invasion and subsequent cell movement is ...

Measurement of Metabolic Rate in Drosophila using Respirometry

Metabolic disorders are a frequent problem affecting human health. Therefore, understanding the mechanisms that regulate metabolism is a crucial scientific task. Many disease causing genes in humans have a fly homologue, making Drosophila a good model to study signaling pathways involved in the development of different disorders. Additionally, the tractability of Drosophila simplifies genetic screens to aid in identifying novel therapeutic targets that may regulate metabolism. In order to perform such a screen a simple and fast method to identify changes in the metabolic state of flies is necessary. In general, carbon dioxide production is a good indicator of substrate oxidation and energy expenditure providing information about metabolic state. In this protocol we introduce a simple method to measure CO2 output from flies. This technique can potentially aid in the identification of genetic perturbations affecting metabolic rate.

Measurement of Metabolic Rate in Drosophila using Respirometry

Metabolic disorders are among one of the most common diseases in humans. The genetically tractable model organism D. melanogaster can be used to identify novel genes that regulate metabolism. This paper describes a relatively simple method which allows studying the metabolic rate in flies by measuring their CO2 production.

قياس معدل الأيض في<em&gt; ذبابة الفاكهة</em&gt; باستخدام قياس التنفس

Metabolic disorders are a frequent problem affecting human health. Therefore, understanding the mechanisms that regulate metabolism is a crucial ...

Functional Characterization of Na+/H+ Exchangers of Intracellular Compartments Using Proton-killing Selection to Express Them at the Plasma Membrane

Endosomal acidification is critical for a wide range of processes, such as protein recycling and degradation, receptor desensitization, and neurotransmitter loading in synaptic vesicles. This acidification is described to be mediated by proton ATPases, coupled to ClC chloride transporters. Highly-conserved electroneutral protons transporters, the Na+/H+ exchangers (NHE) 6, 7 and 9 are also expressed in these compartments. Mutations in their genes have been linked with human cognitive and neurodegenerative diseases. Paradoxically, their roles remain elusive, as their intracellular localization has prevented detailed functional characterization. This manuscript shows a method to solve this problem. This consists of the selection of mutant cell lines, capable of surviving acute cytosolic acidification by retaining intracellular NHEs at the plasma membrane. It then depicts two complementary protocols to measure the ion selectivity and activity of these exchangers: (i) one based on intracellular pH measurements using fluorescence video microscopy, and (ii) one based on the fast kinetics of lithium uptake. Such protocols can be extrapolated to measure other non-electrogenic transporters. Furthermore, the selection procedure presented here generates cells with an intracellular retention defective phenotype. Therefore these cells will also express other vesicular membrane proteins at the plasma membrane. The experimental strategy depicted here may therefore constitute a potentially powerful tool to study other intracellular proteins that will be then expressed at the plasma membrane together with the vesicular Na+/H+ exchangers used for the selection.

Functional Characterization of Na+/H+ Exchangers of Intracellular Compartments Using Proton-killing Selection to Express Them at the Plasma Membrane

The first part of this article shows how to select mutant cell lines expressing vesicular Na+/H+ exchangers at their plasma membrane. The second part provides protocols based on intracellular pH measurements and fast ion uptake, which are used to determine the ion selectivity and the kinetic parameters of these exchangers.

توصيف وظيفي نا<sup&gt; +</sup&gt; / H<sup&gt; +</sup&gt; المبادلات بين الخلايا من المقصورات عن طريق بروتون-مما أسفر عن مقتل اختيار للتعبير عنها في غشاء البلازما

Endosomal acidification is critical for a wide range of processes, such as protein recycling and degradation, receptor desensitization, and ...

Techniques for the Analysis of Extracellular Vesicles Using Flow Cytometry

Extracellular Vesicles (EVs) are small, membrane-derived vesicles found in bodily fluids that are highly involved in cell-cell communication and help regulate a diverse range of biological processes. Analysis of EVs using flow cytometry (FCM) has been notoriously difficult due to their small size and lack of discrete populations positive for markers of interest. Methods for EV analysis, while considerably improved over the last decade, are still a work in progress. Unfortunately, there is no one-size-fits-all protocol, and several aspects must be considered when determining the most appropriate method to use. Presented here are several different techniques for processing EVs and two protocols for analyzing EVs using either individual detection or a bead-based approach. The methods described here will assist with eliminating the antibody aggregates commonly found in commercial preparations, increasing signal&#8211;to-noise ratio, and setting gates in a rational fashion that minimizes detection of background fluorescence. The first protocol uses an individual detection method that is especially well suited for analyzing a high volume of clinical samples, while the second protocol uses a bead-based approach to capture and detect smaller EVs and exosomes.

Many different methods exist for the measurement of extracellular vesicles (EVs) using flow cytometry (FCM). Several aspects should be considered when determining the most appropriate method to use. Two protocols for measuring EVs are presented, using either individual detection or a bead-based approach.

تقنيات لتحليل خارج الخلية الحويصلات عن طريق التدفق الخلوي

Extracellular Vesicles (EVs) are small, membrane-derived vesicles found in bodily fluids that are highly involved in cell-cell communication and help ...

Measurement and Analysis of Extracellular Acid Production to Determine Glycolytic Rate

Extracellular measurement of oxygen consumption and acid production is a simple and powerful way to monitor rates of respiration and glycolysis1. Both mitochondrial (respiration) and non-mitochondrial (other redox) reactions consume oxygen, but these reactions can be easily distinguished by chemical inhibition of mitochondrial respiration. However, while mitochondrial oxygen consumption is an unambiguous and direct measurement of respiration rate2, the same is not true for extracellular acid production and its relationship to glycolytic rate 3-6. Extracellular acid produced by cells is derived from both lactate, produced by anaerobic glycolysis, and CO2, produced in the citric acid cycle during respiration. For glycolysis, the conversion of glucose to lactate- + H+ and the export of products into the assay medium is the source of glycolytic acidification. For respiration, the export of CO2, hydration to H2CO3 and dissociation to HCO3- + H+ is the source of respiratory acidification. The proportions of glycolytic and respiratory acidification depend on the experimental conditions, including cell type and substrate(s) provided, and can range from nearly 100% glycolytic acidification to nearly 100% respiratory acidification 6. Here, we demonstrate the data collection and calculation methods needed to determine respiratory and glycolytic contributions to total extracellular acidification by whole cells in culture using C2C12 myoblast cells as a model.

Glycolysis is a defining metabolic marker in multiple biological systems. Monitoring glycolysis by measuring the extracellular flux of H+ is common, but requires correction to be quantitative and unambiguous. Here, we demonstrate how to gather and correct extracellular flux data to distinguish between respiratory and glycolytic sources of extracellular acidification.

قياس وتحليل حمض خارج الخلية الإنتاج لتحديد معدل حال السكر

Extracellular measurement of oxygen consumption and acid production is a simple and powerful way to monitor rates of respiration and glycolysis1. Both ...

Determination of the Relative Cell Surface and Total Expression of Recombinant Ion Channels Using Flow Cytometry

Inherited or de novo mutations in cation-selective channels may lead to sudden cardiac death. Alteration in the plasma membrane trafficking of these multi-spanning transmembrane proteins, with or without change in channel gating, is often postulated to contribute significantly in this process. It has thus become critical to develop a method to quantify the change of the relative cell surface expression of cardiac ion channels on a large scale. Herein, a detailed protocol is provided to determine the relative total and cell surface expression of cardiac L-type calcium channels CaV1.2 and membrane-associated subunits in tsA-201 cells using two-color fluorescent cytometry assays. Compared with other microscopy-based or immunoblotting-based qualitative methods, flow cytometry experiments are fast, reproducible, and large-volume assays that deliver quantifiable end-points on large samples of live cells (ranging from 104 to 106 cells) with similar cellular characteristics in a single flow. Constructs were designed to constitutively express mCherry at the intracellular C-terminus (thus allowing a rapid assessment of the total protein expression) and express an extracellular-facing hemagglutinin (HA) epitope to estimate the cell surface expression of membrane proteins using an anti-HA fluorescence conjugated antibody. To avoid false negative, experiments were also conducted in permeabilized cells to confirm the accessibility and proper expression of the HA epitope. The detailed procedure provides: (1) design of tagged DNA (deoxyribonucleic acid) constructs, (2) lipid-mediated transfection of constructs in tsA-201 cells, (3) culture, harvest, and staining of non-permeabilized and permeabilized cells, and (4) acquisition and analysis of fluorescent signals. Additionally, the basic principles of flow cytometry are explained and the experimental design, including the choice of fluorophores, titration of the HA antibody and control experiments, is thoroughly discussed. This specific approach offers objective relative quantification of the total and cell surface expression of ion channels that can be extended to study ion pumps and plasma membrane transporters.

Inherited cardiac arrhythmias are often caused by mutations that alter the surface delivery of one or more ion channels. Here, we adapt flow cytometry assays to provide a quantification of the relative total and cell surface protein expression of recombinant ion channels expressed in tsA-201 cells.

تقرير من سطح الخلية النسبي ومجموع التعبير عن قنوات المؤتلف ايون باستخدام التدفق الخلوي

Inherited or de novo mutations in cation-selective channels may lead to sudden cardiac death. Alteration in the plasma membrane trafficking of these ...

Establishment of an Extracellular Acidic pH Culture System

Conditions of the tumor microenvironment, such as hypoxia or nutrient starvation, play critical roles in cancer progression and malignancy. However, the role of acidic extracellular pH in tumor aggressiveness and its underlying mechanism has not been extensively studied compared to hypoxic or nutrient starvation conditions. In addition, a well-defined culture method to mimic the acidic extracellular tumor microenvironment has not been fully reported.
Here we present a simple in vitro culture method to maintain acidic extracellular pH using reduced bicarbonate and increased lactate or HCl concentrations in the culture medium. The medium pH was sustained for at least 24 h and gradually decreased by 72 h following culture of PANC-1 and AsPC-1 pancreatic cancer cells. Three distinct acidic media conditions in this study highly upregulated pH-responsive genes such as MSMO1, INSIG1, and IDI1 compared to hypoxia or nutrient starvation. The upregulation of these genes can be used as a marker of acidic pH. These simple techniques are beneficial to elucidate underlying mechanisms of tumor malignancy under acidic tumor microenvironment. Therefore, our extracellular acidic pH culture system enables discovery of cellular acidic pH responses not only in cancer cells but also in primary cells, such as renal tubular cells, in relation to the other acidic disorders including, diabetic ketoacidosis, lactic acidosis, renal tubular acidosis, and respiratory acidosis.

The acidic tumor microenvironment plays critical roles in tumor progression. To assess the effects of acidic extracellular pH on cancer cells in vitro, we established simple acidic culture systems.

إنشاء درجة الحموضة خارج الخلية الحمضية منظومة الثقافة

Conditions of the tumor microenvironment, such as hypoxia or nutrient starvation, play critical roles in cancer progression and malignancy. However, the ...