Cardiomyopathy is a degenerative disease of the myocardium without obvious systemic etiology. Although therapeutic intervention may offer symptomatic relief, the only successful treatment for cardiomyopathy is cardiac transplantation. Idiopathic dilated cardiomyopathy (DCM) accounts for 87% of diagnosed cardiomyopathies in the United States. Although both systolic and diastolic dysfunction accompany DCM, their underlying cause remains to be established. Indirect evidence suggests that altered Ca2+ cycling by the myocardial sarcoplasmic reticulum (SR) contributes to the functional impairment associated with DCM, but prior to the project described in this proposal, a direct measurement of the Ca2+ content of the SR from human hearts has not been obtained. The goal of this study is to directly measure Ca2+ storage, release, and re-uptake by the human cardiac SR in situ in cardiac muscle from failing (DCM) and non-failing human hearts and to correlate these measurements with parameters of isometric contraction and relaxation in the same muscles. Methods used include a unique combination of functional studies on human trabecular muscles and measurements of Ca2+ within the SR of the same muscles at fixed time points during the contractile cycle by electron probe microanalysis (EPMA). In addition to measuring SR Ca2+, EPMA on rapidly frozen human muscles allows quantification of Ca2+ in the mitochondria and at the level of the myofilaments (A-band) within each cell and provides simultaneous data on other elements of physiological interest (Na, Mg, P, S, Cl and K) within each of these subcellular areas. In order to ensure that functional parameters of contraction and relaxation measured in isolated trabecular muscles are representative of systolic and diastolic cardiac function in vivo, hemodynamic indices of cardiac function prior to transplantation or organ harvest will be obtained from each patient. Correlations will be drawn for each heart between the following parameters: 1) in vivo measures of cardiac function 2) in vitro parameters of muscle contraction and 3) Ca2+ in the SR at fixed time points during the cardiac cycle. This project proposes a direct method for correlating human cardiac muscle function with intracellular calcium homeostasis and provides the first direct test of the hypothesis that defects in SR Ca2+ cycling may be associated with the functional alterations observed in human DCM.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
First Independent Research Support & Transition (FIRST) Awards (R29)
Project #
5R29HL049929-03
Application #
2225977
Study Section
Cardiovascular and Pulmonary Research A Study Section (CVA)
Project Start
1993-07-01
Project End
1998-06-30
Budget Start
1995-07-01
Budget End
1996-06-30
Support Year
3
Fiscal Year
1995
Total Cost
Indirect Cost
Name
Cleveland Clinic Lerner
Department
Type
DUNS #
017730458
City
Cleveland
State
OH
Country
United States
Zip Code
44195
Reiser, P J; Portman, M A; Ning, X H et al. (2001) Human cardiac myosin heavy chain isoforms in fetal and failing adult atria and ventricles. Am J Physiol Heart Circ Physiol 280:H1814-20
Zakhary, D R; Moravec, C S; Bond, M (2000) Regulation of PKA binding to AKAPs in the heart: alterations in human heart failure. Circulation 101:1459-64
Stull, L B; DiIulio, N A; Yu, M et al. (2000) Alterations in cardiac function and gene expression during autoimmune myocarditis in mice. J Mol Cell Cardiol 32:2035-49
Matteo, R G; Moravec, C S (2000) Immunolocalization of annexins IV, V and VI in the failing and non-failing human heart. Cardiovasc Res 45:961-70
Zakhary, D R; Moravec, C S; Stewart, R W et al. (1999) Protein kinase A (PKA)-dependent troponin-I phosphorylation and PKA regulatory subunits are decreased in human dilated cardiomyopathy. Circulation 99:505-10
McConnell, B K; Moravec, C S; Bond, M (1998) Troponin I phosphorylation and myofilament calcium sensitivity during decompensated cardiac hypertrophy. Am J Physiol 274:H385-96
McConnell, B K; Moravec, C S; Morano, I et al. (1997) Troponin I phosphorylation in spontaneously hypertensive rat heart: effect of beta-adrenergic stimulation. Am J Physiol 273:H1440-51
Keller, E; Bond, M; Moravec, C S (1997) Progression of left ventricular hypertrophy does not change the sarcoplasmic reticulum calcium store in the spontaneously hypertensive rat heart. J Mol Cell Cardiol 29:461-9
Moravec, C S; Desnoyer, R W; Milovanovic, M et al. (1997) Mitochondrial calcium content in isolated perfused heart: effects of inotropic stimulation. Am J Physiol 273:H1432-9
Moravec, C S; Keller, E; Bond, M (1995) Decreased inotropic response to beta-adrenergic stimulation and normal sarcoplasmic reticulum calcium stores in the spontaneously hypertensive rat heart. J Mol Cell Cardiol 27:2101-9

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