Proposed mechanisms for decreased myocardial systolic function following ischemic injury include two interrelated processes: impaired energy production, utilization or transfer, and abnormalities of electromechanical coupling related to cation metabolism. Identifying the energetic requirements for maintaining normal transmembrane ion gradients during reperfusion following ischemic insult is an important and unsolved problem. By employing newly developed techniques using 31p, 23Na and 39K NMR spectroscopy, we are now in an unique position to define changes in energetics and transmembrane cation gradients, and their relation, during and following ischemic injury. By using cation NMR techniques developed in this laboratory, we can now define the transsarcolemmal proton, sodium and potassium gradients during and following ischemic injury. In this application, we propose four specific aims using NMR spectroscopy and imaging to define high-energy phosphate content and turnover and the transmembrane gradients of the cations, H+, NA+ K+ and Ca2+, while simultaneously monitoring cardiac performance in postischemic myocardium. 1) to define movements of Na+, K+,H+, and Ca2+ across the sarcolemma in the postischemic myocardium following mild (stunned), moderate and severe ischemia; 2) to construct a kinetic model describing these movements; 3) to relate these changes in cation transport to changes in high-energy phosphate content and turnover rates; and 40 to use 23Na chemical shift imaging in combination with a cationic shift reagent to track the movements of intra-and extracellular Na+ during and following regional ischemia in the isolated heart and the heart in situ.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL043170-04
Application #
3361694
Study Section
Cardiovascular and Pulmonary Research A Study Section (CVA)
Project Start
1989-09-30
Project End
1994-09-29
Budget Start
1992-09-30
Budget End
1993-09-29
Support Year
4
Fiscal Year
1992
Total Cost
Indirect Cost
Name
Brigham and Women's Hospital
Department
Type
DUNS #
071723621
City
Boston
State
MA
Country
United States
Zip Code
02115
Bak, Marianna I; Ingwall, Joanne S (2003) Contribution of Na+/H+ exchange to Na+ overload in the ischemic hypertrophied hyperthyroid rat heart. Cardiovasc Res 57:1004-14
Bak, M I; Ingwall, J S (1998) Regulation of cardiac AMP-specific 5'-nucleotidase during ischemia mediates ATP resynthesis on reflow. Am J Physiol 274:C992-1001
Spencer, R G; Buttrick, P M; Ingwall, J S (1997) Function and bioenergetics in isolated perfused trained rat hearts. Am J Physiol 272:H409-17
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Tian, R; Ingwall, J S (1996) Energetic basis for reduced contractile reserve in isolated rat hearts. Am J Physiol 270:H1207-16
Stewart, L C; Kelly, R A; Atkinson, D E et al. (1995) pH heterogeneity in aged hypertensive rat hearts distinguishes reperfused from persistently ischemic myocardium. J Mol Cell Cardiol 27:321-33
Friedrich, J; Apstein, C S; Ingwall, J S (1995) 31P nuclear magnetic resonance spectroscopic imaging of regions of remodeled myocardium in the infarcted rat heart. Circulation 92:3527-38
Hamman, B L; Bittl, J A; Jacobus, W E et al. (1995) Inhibition of the creatine kinase reaction decreases the contractile reserve of isolated rat hearts. Am J Physiol 269:H1030-6
Neubauer, S; Horn, M; Naumann, A et al. (1995) Impairment of energy metabolism in intact residual myocardium of rat hearts with chronic myocardial infarction. J Clin Invest 95:1092-100

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