Relationship between myocardial metabolites and contractile abnormalities during graded regional ischemia

Phosphorus-31 nuclear magnetic resonance studies of porcine myocardium in vivo

Saul Schaefer, Gregory G. Schwartz, Joel R. Gober, Andrew K. Wong, S. Albert Camacho, Barry Massie, Michael W. Weiner

Research output: Contribution to journalArticle

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Abstract

The mechanisms responsible for changes in myocardial contractility during regional ischemia are unknown. Since changes in high-energy phosphates during ischemia are sensitive to reductions in myocardial blood flow, it was hypothesized that myocardial function under steady-state conditions of graded regional ischemia is closely related to changes in myocardial high-energy phosphates. Therefore, phosphorus-31 nuclear magnetic resonance spectroscopy was employed in an in vivo porcine model of graded coronary stenosis. Simultaneous measurements of regional subendocardial blood flow, high-energy phosphates, pH, and myocardial segment shortening were made during various degrees of regional ischemia in which subendocardial blood flow was reduced by 16-94%. During mild reductions in myocardial blood flow (subendocardial blood flow = 83% of nonischemic myocardium), only the ratio of phosphocreatine to inorganic phosphate (PCr/Pi), Pi, and [H+] were significantly changed from control. PCr, ATP, and PCr/ATP were not significantly reduced from control with mild reductions in blood flow. Changes in myocardial segment shortening were most closely associated with changes in PCr/ Pi (r = 0.94). Pi and [H+] were negatively correlated with segment shortening (r = -0.64 and -0.58, respectively) and increased over twofold when blood flow was reduced by 62%. Thus, these data demonstrate that PCr/Pi is sensitive to reductions in myocardial blood flow and closely correlates with changes in myocardial function. These data are also consistent with a role for Pi or H+ as inhibitors of myocardial contractility during ischemia.

Original languageEnglish (US)
Pages (from-to)706-713
Number of pages8
JournalJournal of Clinical Investigation
Volume85
Issue number3
StatePublished - Mar 1990

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Phosphorus
Myocardium
Magnetic Resonance Spectroscopy
Swine
Ischemia
Phosphates
Adenosine Triphosphate
Phosphocreatine
Coronary Stenosis
Regional Blood Flow

Keywords

  • High-energy phosphates
  • Magnetic resonance spectroscopy
  • Myocardial ischemia
  • Phosphocreatine

ASJC Scopus subject areas

  • Medicine(all)

Cite this

Relationship between myocardial metabolites and contractile abnormalities during graded regional ischemia : Phosphorus-31 nuclear magnetic resonance studies of porcine myocardium in vivo. / Schaefer, Saul; Schwartz, Gregory G.; Gober, Joel R.; Wong, Andrew K.; Albert Camacho, S.; Massie, Barry; Weiner, Michael W.

In: Journal of Clinical Investigation, Vol. 85, No. 3, 03.1990, p. 706-713.

Research output: Contribution to journalArticle

Schaefer, Saul ; Schwartz, Gregory G. ; Gober, Joel R. ; Wong, Andrew K. ; Albert Camacho, S. ; Massie, Barry ; Weiner, Michael W. / Relationship between myocardial metabolites and contractile abnormalities during graded regional ischemia : Phosphorus-31 nuclear magnetic resonance studies of porcine myocardium in vivo. In: Journal of Clinical Investigation. 1990 ; Vol. 85, No. 3. pp. 706-713.
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abstract = "The mechanisms responsible for changes in myocardial contractility during regional ischemia are unknown. Since changes in high-energy phosphates during ischemia are sensitive to reductions in myocardial blood flow, it was hypothesized that myocardial function under steady-state conditions of graded regional ischemia is closely related to changes in myocardial high-energy phosphates. Therefore, phosphorus-31 nuclear magnetic resonance spectroscopy was employed in an in vivo porcine model of graded coronary stenosis. Simultaneous measurements of regional subendocardial blood flow, high-energy phosphates, pH, and myocardial segment shortening were made during various degrees of regional ischemia in which subendocardial blood flow was reduced by 16-94{\%}. During mild reductions in myocardial blood flow (subendocardial blood flow = 83{\%} of nonischemic myocardium), only the ratio of phosphocreatine to inorganic phosphate (PCr/Pi), Pi, and [H+] were significantly changed from control. PCr, ATP, and PCr/ATP were not significantly reduced from control with mild reductions in blood flow. Changes in myocardial segment shortening were most closely associated with changes in PCr/ Pi (r = 0.94). Pi and [H+] were negatively correlated with segment shortening (r = -0.64 and -0.58, respectively) and increased over twofold when blood flow was reduced by 62{\%}. Thus, these data demonstrate that PCr/Pi is sensitive to reductions in myocardial blood flow and closely correlates with changes in myocardial function. These data are also consistent with a role for Pi or H+ as inhibitors of myocardial contractility during ischemia.",
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