Name: assessment of sarcoplasmic reticulum calcium reserve and intracellular diastolic calcium removal in isolated ventricular cardiomyocytes
Uploaded: 2017-09-18T13:00:00
Description: Watch this Scientific Journal Video about Assessment of Sarcoplasmic Reticulum Calcium Reserve and Intracellular Diastolic Calcium Removal in Isolated Ventricular Cardiomyocytes at JoVE.com

This work was supported by grants from the National Natural Science Foundation of China (No. 81100159, Dongwu Lai; 81401147, Juhong Zhang), the Medical and Health Science Program of Zhejiang Province (No. 201646246, Dongwu Lai), and the Health Science and Technology Plan of Hangzhou City (No. 2013A28, Ding Lin).

All animal experiments were performed in accordance with protocols approved by the Institutional Animal Care and Use Committee at Experimental Research Center, China Academy of Chinese Medical Sciences and Zhejiang University.
1. Solution Preparation
<ol>
	<li>Prepare all solutions as described in Table 1.</li>
</ol>
2. Isolation of Left Ventricular (LV) Cardiomyocytes
NOTE: LV cardiomyocytes are isolated enzymatically using ...

<ol>
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Q. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Progressive+decay+of+Ca2++homeostasis+in+the+development+of+diabetic+cardiomyopathy.">Progressive decay of Ca2+ homeostasis in the development of diabetic cardiomyopathy.</a> Cardiovasc Diabetol. 13, 75 (2014).</li><li>Pereira, L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Calcium+signaling+in+diabetic+cardiomyocytes.">Calcium signaling in diabetic cardiomyocytes.</a> Cell calcium. 56 (5), 372-380 (2014).</li><li>Coppini, R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Late+sodium+current+inhibition+reverses+electromechanical+dysfunction+in+human+hypertrophic+cardiomyopathy.">Late sodium current inhibition reverses electromechanical dysfunction in human hypertrophic cardiomyopathy.</a> Circulation. 127 (5), 575-584 (2013).</li><li>Ferrantini, C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=R4496C+RyR2+mutation+impairs+atrial+and+ventricular+contractility.">R4496C RyR2 mutation impairs atrial and ventricular contractility.</a> J Gen Physiol. 147 (1), 39-52 (2016).</li><li>Li, L., Chu, G., Kranias, E. G., Bers, D. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cardiac+myocyte+calcium+transport+in+phospholamban+knockout+mouse+relaxation+and+endogenous+CaMKII+effects.">Cardiac myocyte calcium transport in phospholamban knockout mouse relaxation and endogenous CaMKII effects.</a> Am J Physiol. 274, H1335-H1347 (1998).</li><li>Cheng, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=CaMKII+inhibition+in+heart+failure,+beneficial,+harmful,+or+both.">CaMKII inhibition in heart failure, beneficial, harmful, or both.</a> Am J Physiol Heart Circ Physiol. 302, H1454-H1465 (2012).</li><li>Lai, D., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+Rho+kinase+inhibitor,+fasudil,+ameliorates+diabetes-induced+cardiac+dysfunction+by+improving+calcium+clearance+and+actin+remodeling.">The Rho kinase inhibitor, fasudil, ameliorates diabetes-induced cardiac dysfunction by improving calcium clearance and actin remodeling.</a> J Mol Med (Berl). 95 (2), 155-165 (2017).</li><li>Lai, D., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Stretch+Current-Induced+Abnormal+Impulses+in+CaMKII&#948;+Knockout+Mouse+Ventricular+Myocytes.">Stretch Current-Induced Abnormal Impulses in CaMKII&#948; Knockout Mouse Ventricular Myocytes.</a> J Cardiovasc Electrophysiol. 24 (4), 457-463 (2013).</li><li>Xu, L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Alterations+of+L-type+calcium+current+and+cardiac+function+in+CaMKII{delta}+knockout+mice.">Alterations of L-type calcium current and cardiac function in CaMKII{delta} knockout mice.</a> Circ Res. 107 (3), 398-407 (2010).</li><li>Roussel, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Palmitoyl-carnitine+increases+RyR2+oxidation+and+sarcoplasmic+reticulum+Ca2++leak+in+cardiomyocytes:+Role+of+adenine+nucleotide+translocase.">Palmitoyl-carnitine increases RyR2 oxidation and sarcoplasmic reticulum Ca2+ leak in cardiomyocytes: Role of adenine nucleotide translocase.</a> Biochim Biophys Acta. 1852 (5), 749-758 (2015).</li><li>Yaras, N., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effects+of+diabetes+on+ryanodine+receptor+Ca2++release+channel+(RyR2)+and+Ca2++homeostasis+in+rat+heart.">Effects of diabetes on ryanodine receptor Ca2+ release channel (RyR2) and Ca2+ homeostasis in rat heart.</a> Diabetes. 54 (11), 3082-3088 (2005).</li><li>Hu, Y., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Adenovirus-Mediated+Overexpression+of+O-GlcNAcase+Improves+Contractile+Function+in+the+Diabetic+Heart.">Adenovirus-Mediated Overexpression of O-GlcNAcase Improves Contractile Function in the Diabetic Heart.</a> Circ Res. 96 (9), 1006-1013 (2005).</li></ol>

Calcium flux released from the SR is the major Ca2+ source for systole in the heart. To some extent, the amplitude of SR Ca2+ content and the fractional Ca2+ released from the SR reflect the SR Ca2+ reserve available for cardiac contraction. On the other hand, the Ca2+ reserve of SR depends on the ability of SR Ca2+ reuptake, Ca2+ leak of SR, and their balance across the SR during diastole12,1...

Intracellular calcium ([Ca2+]i) recycling plays a critical role in regulation of systolic and diastolic function in cardiomyocytes1. As we know, the calcium-induced Ca2+ release initiates the excitation-contraction coupling, which translate the electrical signal to contraction. Membrane depolarization activates the sarcolemmal L-type Ca2+ channels, which induce Ca2+ release from SR into the cytoplasm via ryanodine receptors 2 (RyR2). The transient elevated cytoplasmic Ca2+ initiates contraction of myofibrils. During the diastole, cytoplasmic Ca2+ is reuptaken into the SR by means of the SR Ca2+-ATPase 2 (SERCA2) and pumped out of the cardiomyocyte via the Na+-Ca2+ exchanger (NCX)2. This process leads to contraction-relaxation recycling in the cardiomyocyte.
The cardiac SR is an intracellular membrane network that surrounds the contractile machinery. It serves as a Ca2+ reservoir for contraction, and it reabsorbs intracellular Ca2+ during relaxation. The SR Ca2+ reserve available for beats is determinate for cardiac contractility. Meanwhile, the removal of intracellular Ca2+ is critical for cardiac diastole. Under some pathophysiological conditions, such as diabetes and heart failure, impaired Ca2+ clearance and depressed SR Ca2+ store in cardiomyocytes may be involved in the process of cardiac dysfunction2,3,4.
For measuring SR Ca2+ release and diastolic Ca2+ removal in cardiomyocytes, there are two widely used approaches: the integrity of the NCX current based on patch-clamp5,6, and the caffeine-induced Ca2+ pulse based on Ca2+ fluorescence imaging7,8,9. The former approach depends on the fact that the Ca2+ released from the SR is largely pumped out of the cell by NCX. However, this approach is limited by its requirement of advanced equipment and skillful operation. In the present study, we describe a convenient approach to assess SR Ca2+ reserve and Ca2+ removal in myocytes by measuring a caffeine-induced Ca2+ pulse based on a Ca2+ fluorescence imaging system. Briefly, intracellular Ca2+ fluorescence is indicated by Fura-2. By interlinking the stimulation system and perfusion system, we present a program for switching the perfusion and pacing system automatically. 10 mM caffeine was employed to rapidly induce total Ca2+ release in the SR. The exponential decay time constants (Tau) of calcium transients and caffeine-induced calcium pulses were obtained from mono-exponential curve fitting, which reflect the contribution of SERCA and NCX to diastolic Ca2+ removal accordingly.

<table>
	<tbody>
		<tr>
			<td>NaCl</td>
			<td>Alfa Aesar</td>
			<td>E31K43</td>
			<td></td>
		</tr>
		<tr>
			<td>MgCl2</td>
			<td>Alfa Aesar</td>
			<td>I02T070</td>
			<td></td>
		</tr>
		<tr>
			<td>KCl</td>
			<td>Alfa Aesar</td>
			<td>G22u018</td>
			<td></td>
		</tr>
		<tr>
			<td>HEPEs</td>
			<td>Sigma</td>
			<td>SLBM 7880V</td>
			<td></td>
		</tr>
		<tr>
			<td>D-Glucose</td>
			<td>Alfa Aesar</td>
			<td>10189341</td>
			<td></td>
		</tr>
		<tr>
			<td>NaOH</td>
			<td>Alfa Aesar</td>
			<td>10154048</td>
			<td></td>
		</tr>
		<tr>
			<td>KOH</td>
			<td>Alfa Aesar</td>
			<td>10144B17</td>
			<td></td>
		</tr>
		<tr>
			<td>KH2PO4</td>
			<td>Alfa Aesar</td>
			<td>F21S033</td>
			<td></td>
		</tr>
		<tr>
			<td>MgSO4</td>
			<td>Alfa Aesar</td>
			<td>C31U038</td>
			<td></td>
		</tr>
		<tr>
			<td>L-Glutamic</td>
			<td>Alfa Aesar</td>
			<td>10149849</td>
			<td></td>
		</tr>
		<tr>
			<td>Taurine</td>
			<td>Alfa Aesar</td>
			<td>J5407a</td>
			<td></td>
		</tr>
		<tr>
			<td>EGTA</td>
			<td>Sigma</td>
			<td>SLBM6826V</td>
			<td></td>
		</tr>
		<tr>
			<td>Collagenase A</td>
			<td>Roche</td>
			<td>10103586001</td>
			<td></td>
		</tr>
		<tr>
			<td>Collagenase Type II</td>
			<td>Worthington</td>
			<td>45k16005</td>
			<td></td>
		</tr>
		<tr>
			<td>BSA</td>
			<td>Roche</td>
			<td>735094</td>
			<td></td>
		</tr>
		<tr>
			<td>caffeine</td>
			<td>Sigma</td>
			<td>C0750</td>
			<td></td>
		</tr>
		<tr>
			<td>Fura-2 AM</td>
			<td>Invitrogen</td>
			<td>F1201</td>
			<td></td>
		</tr>
		<tr>
			<td>Microscope</td>
			<td>Olympus</td>
			<td>Olympus IX 71</td>
			<td></td>
		</tr>
		<tr>
			<td>Langendorff system</td>
			<td>Beijing Syutime Technology Co</td>
			<td>PlexiThermo-S-LANGC</td>
			<td></td>
		</tr>
		<tr>
			<td>Micromanipulator</td>
			<td>Marchauser</td>
			<td>MM33 links</td>
			<td></td>
		</tr>
		<tr>
			<td>Perfusion chamber</td>
			<td>IonOptix</td>
			<td>FHD</td>
			<td></td>
		</tr>
		<tr>
			<td>Valve Controlled Gravity Perfusion System</td>
			<td>ALA</td>
			<td>VC 3-8</td>
			<td></td>
		</tr>
		<tr>
			<td>valve commander software</td>
			<td>ALA</td>
			<td>VC 3 1.0.1.2</td>
			<td></td>
		</tr>
		<tr>
			<td>Precision flow regulator</td>
			<td>Delta Med</td>
			<td>3204315</td>
			<td></td>
		</tr>
		<tr>
			<td>Multi-Barrel Manifold Perfusion Pencil</td>
			<td>AutoMate Scientific</td>
			<td>04-08-[360]</td>
			<td></td>
		</tr>
		<tr>
			<td>Micron Removable Tip</td>
			<td>AutoMate Scientific</td>
			<td>360um i.d.</td>
			<td></td>
		</tr>
		<tr>
			<td>Fluorescence Measurement and Cell Dimensioning Systems</td>
			<td>IonOptix</td>
			<td>Hyperswitch</td>
			<td></td>
		</tr>
		<tr>
			<td>Recording software</td>
			<td>IonOptix</td>
			<td>IonWizard 6.2.59</td>
			<td></td>
		</tr>
		<tr>
			<td>Stimulator</td>
			<td>IonOptix</td>
			<td>MyoPacer EP</td>
			<td></td>
		</tr>
		<tr>
			<td>Sprague-dawley rats</td>
			<td>Beijing Vital River Laboratory Animal Technology Co.</td>
			<td>SCXK 2016-01-007436</td>
			<td></td>
		</tr>
	</tbody>
</table>

assessment of sarcoplasmic reticulum calcium reserve and intracellular diastolic calcium removal in isolated ventricular cardiomyocytes

Intracellular calcium recycling plays a critical role in regulation of systolic and diastolic function in cardiomyocytes. Cardiac sarcoplasmic reticulum (SR) serves as a Ca2+ reservoir for contraction, which reuptakes intracellular Ca2+ during relaxation. The SR Ca2+ reserve available for beats is determinate for cardiac contractibility, and the removal of intracellular Ca2+ is critical for cardiac diastolic function. Under some pathophysiological conditions, such as diabetes and heart failure, impaired calcium clearance and SR Ca2+ store in cardiomyocytes may be involved in the progress of cardiac dysfunction. Here, we describe a protocol to evaluate SRCa2+ reserve and diastolic Ca2+ removal. Briefly, a single cardiomyocyte was enzymatically isolated, and the intracellular Ca2+ fluorescence indicated by Fura-2 was recorded by a calcium imaging system. To employ caffeine for inducing total SR Ca2+ release, we preset an automatic perfusion switch program by interlinking the stimulation system and the perfusion system. Then, the mono-exponential curve fitting was used for analyzing decay time constants of calcium transients and caffeine-induced calcium pulses. Accordingly, the contribution of the SR Ca2+-ATPase (SERCA) and Na+-Ca2+ exchanger (NCX) to diastolic calcium removal was evaluated.

&#160; &#160; &#160; &#160; &#160; &#160; &#160; Here, we illustrate streptozotocin (STZ)-induced diabetic rats (DM) and age-matched Sprague-Dawley (SD) rats for example. 8-week-old male SD rats (200 &#177; 20 g) received a single intraperitoneal injection of STZ (70 mg/kg, ip) for the DM group or citrate buffer for the control group. One week after STZ administration, rats with blood glucose &#62; 16.7 mmol/L were considered diabetic. After 8 weeks, the LV myocytes were enzymatically iso...

Watch this Scientific Journal Video about Assessment of Sarcoplasmic Reticulum Calcium Reserve and Intracellular Diastolic Calcium Removal in Isolated Ventricular Cardiomyocytes at JoVE.com

Assessment of Sarcoplasmic Reticulum Calcium Reserve and Intracellular Diastolic Calcium Removal in Isolated Ventricular Cardiomyocytes

Intracellular calcium recycling plays a critical role in regulation of systolic and diastolic function in cardiomyocytes. Here, we describe a protocol to evaluate sarcoplasmic reticulum Ca2+ reserve and diastolic calcium removal function in cardiomyocytes by a calcium imaging system.

Intracellular calcium recycling plays a critical role in regulation of systolic and diastolic function in cardiomyocytes. Cardiac sarcoplasmic reticulum ...

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