Name: measuring pressure volume loops in the mouse
Uploaded: 2016-05-02T15:00:00
Description: Watch this Scientific Journal Video about Measuring Pressure Volume Loops in the Mouse at JoVE.com

The author would like to acknowledge funding from NHLBI (K08 HL102066 and R01 HL114832).

Before performing any of the procedures described in this protocol, obtain approval by the local institutional animal care and use committee.
1. Setting Up the Experimental Rig
Note: This procedure is performed on anesthetized animals and the quality of the data is proportional to the quality of the anesthetic support offered to the animal. This first section will detail the equipment and procedures necessary to provide anesthesia to the mouse while p...

<ol>
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There are three critical steps in this procedure: 1) the placement of the endotracheal tube and appropriate ventilation, 2) placement of the jugular IV catheter, and 3) the proper placement of the PV catheter in the left ventricle. Determining the appropriate respiratory rate is an important part of providing ventilatory support. Conscious mice generally maintain alveolar ventilation with rapid shallow breaths. In general, ventilated mice will have much larger tidal volumes. Thus a slower respiratory rate is required. Th...

Cardiovascular disease continues to be a significant cause of mortality and morbidity throughout the world 1. Diseases of the heart present particularly difficult challenges in developing new therapies. Advances in genetics provide for the possibility to identify a multitude of potential genetic contributors to the development of heart disease. The integrative nature of the cardiovascular system requires that these genetic targets be validated in intact animal models. The genetic flexibility and low housing costs of the mouse have brought it to the forefront for the assessment of the physiological role of a given gene. The small size of the mouse presents some unique challenges for the assessment of cardiac function. There are several modalities that can provide information regarding cardiac function, but only the simultaneous measurement of ventricular pressure and volume allows pressure-volume (PV) loop analysis of ventricular function. PV loops allow cardiac function to be analyzed independent of its connection to the vasculature; an important factor in determining the functional role of a particular genetic element.
The assessment of pressure-volume loops has been used both experimentally and clinically for many years and extensive literature exists regarding the analysis of these data sets 2,3. The adaptation of PV loop technology to the mouse has been an important advancement for the understanding of murine cardiac physiology 4-6. Catheter based PV loop technologies couple a pressure transducer and the use of conductance to estimate ventricular volume. The ventricular volume is determined by examining changes in an electrical field generated by the catheter. This method models the ventricle as a cylinder, the height of which is defined by the distance between the electrodes on the catheter and the radius is calculated from conduction of an electrical field through the blood in the ventricle 7-9. The conductance signal measured by the catheter has two components. The first is the conduction through the blood; this varies with the volume of the ventricle and constitutes the primary signal used to determine ventricular volume. The second component results from conduction through and along the wall of the ventricle. This is called parallel conductance and must be removed in order to determine the absolute ventricular volume. There are two commercially available systems for the collection of pressure-volume data in the research laboratory and the method used to calculate and remove the parallel conductance is the primary difference between them 6,10,11. Conductance catheters require the injection of hypertonic saline for the calculation of parallel conductance. This injection transiently changes the conductivity of the blood in the ventricle, while the conductivity of the wall remains constant. From this data it is possible to determine the component of the conductance signal that originates from the blood and what comes from the ventricular wall. This approach assumes that parallel conductance does not vary during the cardiac cycle. The admittance method relies on phase changes in the electrical field to assess the contribution of the ventricular wall to the overall volume signal. This method relies on a variety of predetermined constants for the conductivity of the blood and myocardium to determine the final volume, but makes continuous measures of parallel conductance during the cardiac cycle. Both of these systems provide good estimates of left ventricular volume and the differences between them are not likely to be physiologically significant. The cylindrical model of the ventricle and other assumptions render these catheter-based approaches not as accurate as other modalities, but this data is provided on a beat-by-beat basis that is essential for the assessment of load independent measures of cardiac function.
The procedure outlined here is used in my laboratory and has provided data for a large number of studies examining the basic pathophysiological mechanisms of dystrophic cardiomyopathy 12-18. The procedure outlined below is one of two that can be used to obtain PV loop data. While many of the principles are applicable for either approach, this protocol will focus on an open-chest apical approach; a closed chest protocol has been detailed elsewhere 19,20. While the procedure will be described in detail, the important overarching principles are to expose the heart with minimal damage to either the heart or the lungs. Throughout the protocol it is important to remember that this is a non-survival procedure and that having a good exposure of the heart is critically important for the proper placement of the catheter.

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	<tbody>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Dumont 5/45 (2)</td>
			<td style="width:127px;">Fine Science Tools</td>
			<td style="width:119px;">11251-33</td>
			<td style="width:63px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Vessel Dilating Forceps</td>
			<td style="width:127px;">Fine Science Tools</td>
			<td style="width:119px;">18153-11</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Castroviejo Micro Dissecting Spring Scissor</td>
			<td style="width:127px;">Roboz Instruments</td>
			<td style="width:119px;">RS-5668</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Octogon Forceps - Serrated/Curved</td>
			<td style="width:127px;">Fine Science Tools</td>
			<td style="width:119px;">11041-08</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Octogon Forceps - Serrated/Straight</td>
			<td style="width:127px;">Fine Science Tools</td>
			<td style="width:119px;">11040-08</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Dissector Scissors- Heavy Blade</td>
			<td style="width:127px;">Fine Science Tools</td>
			<td style="width:119px;">14082-09</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Transpore Surgical Tape</td>
			<td style="width:127px;">3M</td>
			<td style="width:119px;">1527-1</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">3-0 Silk Suture</td>
			<td style="width:127px;">Fine Science Tools</td>
			<td style="width:119px;">18020-30</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">TOPO Ventilator</td>
			<td style="width:127px;">Kent Scientific</td>
			<td style="width:119px;">TOPO</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Martin ME 102 Electrosurgical Unit</td>
			<td style="width:127px;">Harvard Apparatus</td>
			<td style="width:119px;">PY2 72-2484</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Syringe Pump</td>
			<td style="width:127px;">Lucca Technologies</td>
			<td style="width:119px;">GenieTouch</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Stereomicroscope with boom stand</td>
			<td style="width:127px;">Nikon</td>
			<td style="width:119px;">SMZ-800N</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Thermocouple Thermometer</td>
			<td style="width:127px;">Cole Parmer</td>
			<td style="width:119px;">EW-91100-40</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">T/Pump Warm Water Recirculator</td>
			<td style="width:127px;">Kent Scientific</td>
			<td style="width:119px;">TP-700</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:216px;">ADVantage Pressure-Volume System</td>
			<td style="width:127px;">Transonic</td>
			<td style="width:119px;">ADV500</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Data Acquision and Analysis</td>
			<td style="width:127px;">DSI</td>
			<td style="width:119px;">Ponemah ACQ-16</td>
			<td></td>
		</tr>
	</tbody>
</table>

measuring pressure volume loops in the mouse

Understanding the causes and progression of heart disease presents a significant challenge to the biomedical community. The genetic flexibility of the mouse provides great potential to explore cardiac function at the molecular level. The mouse&#39;s small size does present some challenges in regards to performing detailed cardiac phenotyping. Miniaturization and other advancements in technology have made many methods of cardiac assessment possible in the mouse. Of these, the simultaneous collection of pressure and volume data provides a detailed picture of cardiac function that is not available through any other modality. Here a detailed procedure for the collection of pressure-volume loop data is described. Included is a discussion of the principles underlying the measurements and the potential sources of error. Anesthetic management and surgical approaches are discussed in great detail as they are both critical to obtaining high quality hemodynamic measurements. The principles of hemodynamic protocol development and relevant aspects of data analysis are also addressed.

By convention, volume is plotted on the X-axis and pressure on the Y-axis as in Figure 1. The pressure-volume loops resulting from plotting pressure against volume should resemble a rectangle, the vertical edges representing isovolumic changes in pressure (i.e., when both mitral and aortic valves are closed). The bottom horizontal represents ventricular filling through the mitral valve and the upper horizontal portion represents ventricular emptying through the a...

Watch this Scientific Journal Video about Measuring Pressure Volume Loops in the Mouse at JoVE.com

Measuring Pressure Volume Loops in the Mouse

This manuscript describes a detailed protocol for the collection of pressure-volume data from the mouse.

Understanding the causes and progression of heart disease presents a significant challenge to the biomedical community. The genetic flexibility of the ...

The overall goal of measuring pressure volume loops in the mouse is to obtain a detailed assessment of cardiac function. This method is useful for the physiological characterization of mice harboring specific genetic manipulations, which in turn can produce insights into the role of specific proteins in cardiac function. The main advantage of this technique is that it provides a detailed assessment of contractile function that is not available through other methodologies.Once the mouse is prepped for surgery, begin by making an incision at the sternal notch extending from about five millimeters right of the midline to about five millimeters left of the midline. Make a second incision extending along the right edge of the first rostrally to about two millimeters coddled to the end of the mandible. Then make a third incision extending from the rostral end of the second incision to about five millimeters right of midline.And retract the resulting skin flap to the right to expose the underlined tissues. Next, under a dissecting microscope, blunt dissect the parotide and sub-mandibular salivary glands at the midline to expose the underlining musculature overlining the trachea. Then bluntly separate the right and left sternal hyoideus muscles.When the trachea is visible, pass a ten centimeter piece of three-zero silk suture under the throat tissue, taking care not to include the esophagus. Using a 20 gauge needle, make a wide incision in the gap just coddle to the larynx before the first tracheal ring. Then immediately remove the anesthesia mask from the animal, and carefully insert the endotracheal tube into the trachea.Once the tube has been secured, extend the left edge of the original skin incision down to the xiphoid process and across the midline to about one point five centimeters right of the midline. Next, use blunt dissection to retract the skin flap laterally exposing the underline musculature. And use vessel dilating forceps to isolate the insertion of the pectoralis major on the right side near the coddle aspect of the sternum.Cauterize and cut the muscle. Then cut through the pectoralis major along its attachment to the sternum. And undermine the latissimus dorsi on the same side.Retract the cut end cranially to reveal the ribs. And use a pair of sharp forceps to carefully dissect down through the intercostal muscle layers to enter the chest. Once the plural space has been opened, carefully insert the blunt tip vessel dilators and lift the chest wall with gentle upward force.Now, cut laterally along the intercostal muscles taking care not to cut the lung lobe and extend the incision medially, keeping three to four millimeters lateral of the midline to avoid the internal mammary artery running parallel to the sternum. Then place a saline-soaked small cotton-tipped applicator through the incision toward the midline and provide a gentle upward traction to pull the chest wall away from the underline structures. Carefully use a cautery to cut through the chest wall beginning at the medial edge of the incision and ending about one centimeter lateral of the midline on the left side.Once the tissue has been thoroughly cauterized, use scissors to carefully cut through the sternum. The apex of the heart should be clearly visible. Then, using blunt dissection, disrupt the pericardium and identify the caudal vena cava.To place the jugular vein catheter, orient a 30-gauge needle catheter attached to a syringe containing ten percent albumin such that the needle lies upon the jugular vein on its own, bevel side up. To visualize the jugular vein, grasp the needle with forceps in one hand and retract the salivary gland with tissue forceps in the other. Apply gentle traction to the tissue surrounding the diesel jugular vein to create tension on the vessel wall.Then, using a shallow angle of approach, carefully insert the needle into the vein and advance the tip three to four millimeters into the vessel. When the catheter is in position, secure the needle to the underline salivary glands using surgical glue and begin infusing the albumin solution. To place the pressure volume catheter, first, move a syringe containing equilibrated saline solution and the pressure volume catheter next to the mouse with the catheter tip at roughly the same height as the heart and zero the pressure reading.Next, using a saline-soaked small cotton-tipped applicator, maneuver the heart to visualize the apex and use a 25-gauge needle to make a stab incision as close to the center of the apex as possible. Following the removal of the needle, quickly but gently insert the catheter through the incision. The ventricular pressure volume loops can then be measured.Following the placement of the catheter, turn the anesthesia down to illuminate the cardio dipressive effects that the anesthesia may be having. If there was excessive blood loss during the procedure, you can simply increase the volume of albumin infused. By convention, the volume is plotted on the X-axis and the pressure on the y-axis.Pressure volume loops resulting from plotting the pressure against the volume should resemble a rectangle with the vertical edges representing the isovolumic changes in the pressure. The bottom horizontal side representing the ventricular filling through the mitral valve and the upper horizontal side representing the ventricular emptying through the aortic valve. In a healthy wild type mouse, left ventricular pressures of 90 to 110 millimeters of mercury are expected with a maximal rate of a maximum derivative of pressure of 8000 to 12000 millimeters of mercury per second.Further, one of the most common artifacts of measurement that can complicate the analysis of pressure volume data is catheter entrapment which is evident as a spike in pressure at the end of systole likely resulting from the direct compression of the pressure transducer by a papillary muscle or other dynamic structure within the ventricle. While performing this procedure, it is important to remember to continuously monitor the mouse to ensure a sufficient anesthetic depth. Once mastered, this technique can be completed in roughly an hour depending on the protocol used after the catheter placement.Following the completion of this procedure, infusions of experimental compounds can be used to assess their affects on cardiac function. After watching this video, you should have a good understanding of how to surgically place a pressure volume catheter in the left ventricle of the mouse and obtain high quality pressure volume loops for cardiac analysis.

measuring-pressure-volume-loops-in-the-mouse

Research

JoVE Journal

Biology

Measuring Blood Pressure in Mice using Volume Pressure Recording, a Tail-cuff Method

The CODA 8-Channel High Throughput Non-Invasive Blood Pressure system measures the blood pressure in up to 8 mice or rats simultaneously. The CODA tail-cuff system uses Volume Pressure Recording (VPR) to measure the blood pressure by determining the tail blood volume. A specially designed differential pressure transducer and an occlusion tail-cuff measure the total blood volume in the tail without the need to obtain the individual pulse signal. Special attention is afforded to the length of the occlusion cuff in order to derive the most accurate blood pressure readings. VPR can easily obtain readings on dark-skinned rodents, such as C57BL6 mice and is MRI compatible. The CODA system provides you with measurements of six (6) different blood pressure parameters; systolic and diastolic blood pressure, heart rate, mean blood pressure, tail blood flow, and tail blood volume. Measurements can be made on either awake or anesthetized mice or rats. The CODA system includes a controller, laptop computer, software, cuffs, animal holders, infrared warming pads, and an infrared thermometer. There are seven different holder sizes for mice as small as 8 grams to rats as large as 900 grams.

The CODA 8-Channel High Throughput Non-Invasive Blood Pressure system measures the blood pressure in up to 8 mice or rats simultaneously. This tail-cuff system uses Volume Pressure Recording (VPR) to measure the blood pressure by determining the tail blood volume.

The CODA 8-Channel High Throughput Non-Invasive Blood Pressure system measures the blood pressure in up to 8 mice or rats simultaneously. The CODA ...

Catheterization of Intestinal Loops in Ruminants

The intestine is a complex structure that is involved not only in absorption of nutrients, but also acts as a barrier between the individual and the outside world. As such, the intestine plays a pivotal role in immunosurveillance and protection from enteric pathogens. Investigating intestinal physiology and immunology commonly employs 'intestinal loops' as an experimental model. The majority of these loop models are non-recovery surgical procedures that study short-term (&lt;24 hr) changes in the intestine (1-3). We previously created a recovery intestinal loop model to specifically measure long-term (&lt;6 mo) immunological changes in the intestine of sheep following exposure to vaccines, adjuvants, and viruses (4). This procedure localized treatments to a specific 'loop', allowing us to sample this area of the intestine. A significant drawback of this method is the single window of opportunity to administer treatments (i.e. at the time of surgery). Furthermore, samples of both the intestinal mucosa and luminal contents can only be taken at the termination of the project. Other salient limitations of the above model are that the surgical manipulation and requisite post-operative measures (e.g. administration of antibiotics and analgesics) can directly affect the treatment itself and/or alter immune function, thereby confounding results. Therefore, we modified our intestinal loop model by inserting long-term catheters into the loops. Sheep recover fully from the procedure, and are unaffected by the exteriorized catheters. Notably, the establishment of catheters in loops allows us to introduce multiple treatments over an extended interval, following recovery from surgery and clearance of drugs administered during surgery and the post-operative period.

We describe a novel surgical method for catheterizing 'intestinal loops' within the ileum of sheep. Once animals have recovered from surgery and have cleared antibiotics and analgesics, multiple treatments can be deposited directly in loops via the catheters.

The intestine is a complex structure that is involved not only in absorption of nutrients, but also acts as a barrier between the individual and the ...

In vivo Imaging and Therapeutic Treatments in an Orthotopic Mouse Model of Ovarian Cancer

Human cancer and response to therapy is better represented in orthotopic animal models. This paper describes the development of an orthotopic mouse model of ovarian cancer, treatment of cancer via oral delivery of drugs, and monitoring of tumor cell behavior in response to drug treatment in real time using in vivo imaging system. In this orthotopic model, ovarian tumor cells expressing luciferase are applied topically by injecting them directly into the mouse bursa where each ovary is enclosed. Upon injection of D-luciferin, a substrate of firefly luciferase, luciferase-expressing cells generate bioluminescence signals. This signal is detected by the in vivo imaging system and allows for a non-invasive means of monitoring tumor growth, distribution, and regression in individual animals. Drug administration via oral gavage allows for a maximum dosing volume of 10 mL/kg body weight to be delivered directly to the stomach and closely resembles delivery of drugs in clinical treatments. Therefore, techniques described here, development of an orthotopic mouse model of ovarian cancer, oral delivery of drugs, and in vivo imaging, are useful for better understanding of human ovarian cancer and treatment and will improve targeting this disease.

In vivo Imaging and Therapeutic Treatments in an Orthotopic Mouse Model of Ovarian Cancer

Orthotopic animal models of ovarian cancer replicate better human disease and therefore enhance our understanding of cancer progression and tumor response to therapy. A mouse model receives an intrabursal injection of luciferase-expressing ovarian tumor cells. Treatment is administered via oral gavage. Tumor growth is monitored by in vivo imaging system.

Human cancer and response to therapy is better represented in orthotopic animal models.  This paper describes the development of an orthotopic mouse model ...

Measuring Caenorhabditis elegans Life Span in 96 Well Microtiter Plates

Lifespan is a biological process regulated by several genetic pathways. One strategy to investigate the biology of aging is to study animals that harbor mutations in components of age-regulatory pathways. If these mutations perturb the function of the age-regulatory pathway and therefore alter the lifespan of the entire organism, they provide important mechanistic insights1-3.
Another strategy to investigate the regulation of lifespan is to use small molecules to perturb age-regulatory pathways. To date, a number of molecules are known to extend lifespan in various model organisms and are used as tools to study the biology of aging4-16. The number of molecules identified thus far is small compared to the genetic "toolset" that is available to study the biology of aging.
Caenorhabditis elegans is one of the principle models used to study aging because of its excellent genetics and short lifespan of three weeks. More recently, C.elegans has emerged as a model organism for phenotype based drug screens5,7,16-20 because of its small size and its ability to grow in microtiter plates.
Here we present an assay to measure C.elegans lifespan in 96 well microtiter plates. The assay was developed and successfully used to screen large libraries for molecules that extend C.elegans lifespan7. The reliability of the assay was evaluated in multiple tests: first, by measuring the lifespan of wild type animals grown at different temperatures; second, by measuring the lifespan of mutants with altered lifespans; third, by measuring changes in lifespan in response to different concentrations of the antidepressant Mirtazepine. Mirtazepine has previously been shown to extend lifespan in C.elegans7. The results of these tests show that the assay is able to replicate previous findings from other assays and is quantitative. The microtiter format also makes this lifespan assay compatible with automated liquid handling systems and allows integration into automated platforms.

Measuring Caenorhabditis elegans Life Span in 96 Well Microtiter Plates

In this protocol we present a method to measure Caenorhabditis elegans lifespan in 96 well microtiter plates.

Lifespan is a biological process regulated by several genetic pathways. One strategy to investigate the biology of aging is to study animals that harbor ...

Generation of Mice Derived from Induced Pluripotent Stem Cells

The production of induced pluripotent stem cells (iPSCs) from somatic cells provides a means to create valuable tools for basic research and may also produce a source of patient-matched cells for regenerative therapies. iPSCs may be generated using multiple protocols and derived from multiple cell sources. Once generated, iPSCs are tested using a variety of assays including immunostaining for pluripotency markers, generation of three germ layers in embryoid bodies and teratomas, comparisons of gene expression with embryonic stem cells (ESCs) and production of chimeric mice with or without germline contribution2. Importantly, iPSC lines that pass these tests still vary in their capacity to produce different differentiated cell types2. This has made it difficult to establish which iPSC derivation protocols, donor cell sources or selection methods are most useful for different applications.
The most stringent test of whether a stem cell line has sufficient developmental potential to generate all tissues required for survival of an organism (termed full pluripotency) is tetraploid embryo complementation (TEC)3-5. Technically, TEC involves electrofusion of two-cell embryos to generate tetraploid (4n) one-cell embryos that can be cultured in vitro to the blastocyst stage6. Diploid (2n) pluripotent stem cells (e.g. ESCs or iPSCs) are then injected into the blastocoel cavity of the tetraploid blastocyst and transferred to a recipient female for gestation (see Figure 1). The tetraploid component of the complemented embryo contributes almost exclusively to the extraembryonic tissues (placenta, yolk sac), whereas the diploid cells constitute the embryo proper, resulting in a fetus derived entirely from the injected stem cell line.
Recently, we reported the derivation of iPSC lines that reproducibly generate adult mice via TEC1. These iPSC lines give rise to viable pups with efficiencies of 5-13%, which is comparable to ESCs3,4,7 and higher than that reported for most other iPSC lines8-12. These reports show that direct reprogramming can produce fully pluripotent iPSCs that match ESCs in their developmental potential and efficiency of generating pups in TEC tests. At present, it is not clear what distinguishes between fully pluripotent iPSCs and less potent lines13-15. Nor is it clear which reprogramming methods will produce these lines with the highest efficiency. Here we describe one method that produces fully pluripotent iPSCs and "all- iPSC" mice, which may be helpful for investigators wishing to compare the pluripotency of iPSC lines or establish the equivalence of different reprogramming methods.

Generating induced pluripotent stem cell (iPSC) lines produces lines of differing developmental potential even when they pass standard tests for pluripotency. Here we describe a protocol to produce mice derived entirely from iPSCs, which defines the iPSC lines as possessing full pluripotency1.

The production of induced pluripotent stem cells (iPSCs) from somatic cells provides a means to create valuable tools for basic research and may also ...

Measuring the Osmotic Water Permeability Coefficient (Pf) of Spherical Cells: Isolated Plant Protoplasts as an Example

Studying AQP regulation mechanisms is crucial for the understanding of water relations at both the cellular and the whole plant levels. Presented here is a simple and very efficient method for the determination of the osmotic water permeability coefficient (Pf) in plant protoplasts, applicable in principle also to other spherical cells such as frog oocytes. The first step of the assay is the isolation of protoplasts from the plant tissue of interest by enzymatic digestion into a chamber with an appropriate isotonic solution. The second step consists of an osmotic challenge assay: protoplasts immobilized on the bottom of the chamber are submitted to a constant perfusion starting with an isotonic solution and followed by a hypotonic solution. The cell swelling is video recorded. In the third step, the images are processed offline to yield volume changes, and the time course of the volume changes is correlated with the time course of the change in osmolarity of the chamber perfusion medium, using a curve fitting procedure written in Matlab (the &#8216;PfFit&#8217;), to yield Pf.

Measuring the Osmotic Water Permeability Coefficient Pf of Spherical Cells: Isolated Plant Protoplasts as an Example

Measuring the osmotic water permeability coefficient (Pf) of cells can help understand the regulatory mechanisms of aquaporins (AQPs). Pf determination in spherical plant cell protoplasts presented here involves protoplasts isolation and numerical analysis of their initial rate of volume change as a result of an osmotic challenge during constant bath perfusion.

Studying AQP regulation mechanisms is crucial for the understanding of water relations at both the cellular and the whole plant levels. Presented here is ...

Measuring Glutathione-induced Feeding Response in Hydra

Hydra is among the most primitive organisms possessing a nervous system and chemosensation for detecting reduced glutathione (GSH) for capturing the prey. The movement of prey organisms causes mechanosensory discharge of the stinging cells called nematocysts from hydra, which are inserted into the prey. The feeding response in hydra, which includes curling of the tentacles to bring the prey towards the mouth, opening of the mouth and consequent engulfing of the prey, is triggered by GSH present in the fluid released from the injured prey. To be able to identify the molecular mechanism of the feeding response in hydra which is unknown to date, it is necessary to establish an assay to measure the feeding response. Here, we describe a simple method for the quantitation of the feeding response in which the distance between the apical end of the tentacle and mouth of hydra is measured and the ratio of such distance before and after the addition of GSH is determined. The ratio, called the relative tentacle spread, was found to give a measure of the feeding response. This assay was validated using a starvation model in which starved hydra show an enhanced feeding response in comparison with daily fed hydra.

Here we describe a simple assay for the quantification of the feeding response in hydra induced by the reduced form of glutathione. This assay relies on measuring the distance between the apical end of the tentacle and mouth of hydra.

Hydra is among the most primitive organisms possessing a nervous system and chemosensation for detecting reduced glutathione (GSH) for capturing the prey. ...

Cardiac Pressure-Volume Loop Analysis Using Conductance Catheters in Mice

Cardiac pressure-volume loop analysis is the &#8220;gold-standard&#8221; in the assessment of load-dependent and load-independent measures of ventricular systolic and diastolic function. Measures of ventricular contractility and compliance are obtained through examination of cardiac response to changes in afterload and preload. These techniques were originally developed nearly three decades ago to measure cardiac function in large mammals and humans. The application of these analyses to small mammals, such as mice, has been accomplished through the optimization of microsurgical techniques and creation of conductance catheters. Conductance catheters allow for estimation of the blood pool by exploiting the relationship between electrical conductance and volume. When properly performed, these techniques allow for testing of cardiac function in genetic mutant mouse models or in drug treatment studies. The accuracy and precision of these studies are dependent on careful attention to the calibration of instruments, systematic conduct of hemodynamic measurements and data analyses. We will review the methods of conducting pressure-volume loop experiments using a conductance catheter in mice.

Cardiac pressure-volume loop analysis is the most comprehensive way to measure cardiac function in the intact heart. We describe a technique to perform and analyze cardiac pressure volume loops, using conductance catheters.

Cardiac pressure-volume loop analysis is the &#8220;gold-standard&#8221; in the assessment of load-dependent and load-independent measures of ventricular ...

Measuring the Stiffness of Ex Vivo Mouse Aortas Using Atomic Force Microscopy

Arterial stiffening is a significant risk factor and biomarker for cardiovascular disease and a hallmark of aging. Atomic force microscopy (AFM) is a versatile analytical tool for characterizing viscoelastic mechanical properties for a variety of materials ranging from hard (plastic, glass, metal, etc.) surfaces to cells on any substrate. It has been widely used to measure the stiffness of cells, but less frequently used to measure the stiffness of aortas. In this paper, we will describe the procedures for using AFM in contact mode to measure the ex vivo elastic modulus of unloaded mouse arteries. We describe our procedure for isolation of mouse aortas, and then provide detailed information for the AFM analysis. This includes step-by-step instructions for alignment of the laser beam, calibration of the spring constant and deflection sensitivity of the AFM probe, and acquisition of force curves. We also provide a detailed protocol for data analysis of the force curves.

Measuring the Stiffness of Ex Vivo Mouse Aortas Using Atomic Force Microscopy

We present detailed protocols for isolation of aortas from mouse and measurement of their elastic modulus using atomic force microscopy.

Arterial stiffening is a significant risk factor and biomarker for cardiovascular disease and a hallmark of aging. Atomic force microscopy (AFM) is a ...

The Mouse Isolated Perfused Kidney Technique

The mouse isolated perfused kidney (MIPK) is a technique for keeping a mouse kidney under ex vivo conditions perfused and functional for 1 hr. This is a prerequisite for studying the physiology of the isolated organ and for many innovative applications that may be possible in the future, including perfusion decellularization for kidney bioengineering or the administration of anti-rejection or genome-editing drugs in high doses to prime the kidney for transplantation. During the time of the perfusion, the kidney can be manipulated, renal function can be assessed, and various pharmaceuticals administered. After the procedure, the kidney can be transplanted or processed for molecular biology, biochemical analysis, or microscopy.
This paper describes the perfusate and the surgical technique needed for the ex vivo perfusion of mouse kidneys. Details of the perfusion apparatus are given and data are presented showing the viability of the kidney&#39;s preparation: renal blood flow, vascular resistance, and urine data as functional, transmission electron micrographs of different nephron segments as morphological readouts, and western blots of transport proteins of different nephron segments as molecular readout.

The mouse isolated perfused kidney (MIPK) is a technique for keeping a mouse kidney under ex vivo conditions perfused and functional for 1 hr. The buffers and surgical technique are described in detail.

The mouse isolated perfused kidney (MIPK) is a technique for keeping a mouse kidney under ex vivo conditions perfused and functional for 1 hr. This is a ...