Alterations in expression of sarcoplasmic reticulum calcium ATPase, and the sodium calcium exchanger have been reported to occur during ventricular hypertrophy, and could have functional effects which may contribute to the progression from hypertrophy to failure. Work described in this project will test the hypotheses that 1) sarcoplasmic reticulum function is decreased, and 2) that sodium calcium exchange activity is increased in intact single ventricular myocytes isolated from failing ventricular myocardium. Ventricular myocytes will be obtained from normal and failing mouse, rabbit, and human ventricular myocardium. Ventricular myocytes from human myocardium will be isolated using a novel technique which employs a vibratome to cut 400 mum thin sections, in the presence of BDM to inhibit cutting injury. This facilitates enzymatic dissociation of Ca2+-tolerant cells from small biopsy specimens. Sodium calcium exchanger activity will be quantitated by measuring the maximum sodium calcium exchange current per unit cell surface area produced by abrupt exposure of voltage clamped isolated myocytes to zero sodium solution containing 2.7 mM calcium. A novel fast solution switcher is used to produce a change in the medium bathing a single myocyte within 7 milliseconds in these experiments. Sarcoplasmic reticulum function in isolated single myocytes will be assessed by inducing contraction of myocytes by abrupt exposure zero sodium, zero calcium KCI solution, and then measuring the rate of relaxation, and the rate of fall in cytosolic free calcium. The latter will be measured with indo-1. This approach allows assessment of the rate at which the sarcoplasmic reticulum can sequester calcium within a single ventricular myocyte under conditions in which, after initial calcium release is triggered by transient influx of calcium from the extracellular space, the sodium calcium exchanger is disabled by the elimination of extracellular sodium. In addition, in myocytes in which SR function is studied, the contractility of isolated myocytes will be assessed by measurement of fractional shortening at different pacing rates, with a video motion detection. This approach should allow determination of the extent to which isolated myocyte contractile performance is impaired in myocytes obtained from failing myocardium, as well as the possible contributions of altered sodium calcium exchanger and SR function.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Specialized Center (P50)
Project #
5P50HL053773-04
Application #
6273023
Study Section
Project Start
1998-01-26
Project End
1998-12-31
Budget Start
1997-10-01
Budget End
1998-09-30
Support Year
4
Fiscal Year
1998
Total Cost
Indirect Cost
Name
University of California San Diego
Department
Type
DUNS #
077758407
City
La Jolla
State
CA
Country
United States
Zip Code
92093
Hirai, Maretoshi; Cattaneo, Paola; Chen, Ju et al. (2016) Revisiting Preadolescent Cardiomyocyte Proliferation in Mice. Circ Res 118:916-919
Swaney, James S; Patel, Hemal H; Yokoyama, Utako et al. (2006) Focal adhesions in (myo)fibroblasts scaffold adenylyl cyclase with phosphorylated caveolin. J Biol Chem 281:17173-9
Swaney, James S; Roth, David M; Olson, Erik R et al. (2005) Inhibition of cardiac myofibroblast formation and collagen synthesis by activation and overexpression of adenylyl cyclase. Proc Natl Acad Sci U S A 102:437-42
Insel, Paul A; Head, Brian P; Ostrom, Rennolds S et al. (2005) Caveolae and lipid rafts: G protein-coupled receptor signaling microdomains in cardiac myocytes. Ann N Y Acad Sci 1047:166-72
Head, Brian P; Patel, Hemal H; Roth, David M et al. (2005) G-protein-coupled receptor signaling components localize in both sarcolemmal and intracellular caveolin-3-associated microdomains in adult cardiac myocytes. J Biol Chem 280:31036-44
Riddle, Evan L; Schwartzman, Raul A; Bond, Meredith et al. (2005) Multi-tasking RGS proteins in the heart: the next therapeutic target? Circ Res 96:401-11
Lorenzen-Schmidt, Ilka; Stuyvers, Bruno D; ter Keurs, Henk E D J et al. (2005) Young MLP deficient mice show diastolic dysfunction before the onset of dilated cardiomyopathy. J Mol Cell Cardiol 39:241-50
Ostrom, Rennolds S; Bundey, Richard A; Insel, Paul A (2004) Nitric oxide inhibition of adenylyl cyclase type 6 activity is dependent upon lipid rafts and caveolin signaling complexes. J Biol Chem 279:19846-53
Tang, Chih-Min; Insel, Paul A (2004) GPCR expression in the heart; ""new"" receptors in myocytes and fibroblasts. Trends Cardiovasc Med 14:94-9
Roth, David M; Lai, N Chin; Gao, Mei Hua et al. (2004) Indirect intracoronary delivery of adenovirus encoding adenylyl cyclase increases left ventricular contractile function in mice. Am J Physiol Heart Circ Physiol 287:H172-7

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