TY - JOUR
T1 - Metabolic and functional consequences of blunted myocardial reactive hyperemia
AU - Schwartz, G. G.
AU - Schaefer, Saul
AU - Trocha, S. D.
AU - Steinman, S.
AU - Gober, J.
AU - Garcia, J.
AU - Massie, B.
AU - Weiner, M. W.
PY - 1991
Y1 - 1991
N2 - This study determined whether the rapidity of myocardial metabolic and contractile recovery after brief coronary occlusion depends upon the intensity of reactive hyperemia. We also tested the hypothesis that coronary flow rate modulates contractility after brief myocardial ischemia, independent of changes in phosphorus metabolites. Eight open-chest pigs were studied with phosphorus-31 nuclear magnetic resonance (NMR) spectroscopy with 14 s time resolution. After a 29-s anterior descending coronary occlusion, peak Doppler coronary flow velocity was alternately unrestricted (normal hyperemia, 443 ± 40% of control) or limited to 159 ± 9% of control. During 29 s coronary occlusion, phosphocreatine-to-inorganic phosphate ratio (PCr/P(i)) and systolic segment shortening in the ischemic region fell to 28 ± 4 and 7 ± 7% of control, respectively. With normal hyperemia, PCr/P(i) and segment shortening recovered within 29 s. With blunted hyperemia, recovery of both parameters was delayed an additional 29-43 s, associated with reduced subendocardial blood flow (measured with radioactive microspheres) and persistent intracellular acidosis. However, the relationship between segment shortening and PCr/P(i) was unaffected by the intensity of reactive hyperemia. Thus blunted reactive hyperemia significantly delays metabolic and contractile recovery from brief ischemia, probably via transient maldistribution of transmural perfusion. However, coronary blood flow rate does not independently modulate contractility after brief reversible ischemia.
AB - This study determined whether the rapidity of myocardial metabolic and contractile recovery after brief coronary occlusion depends upon the intensity of reactive hyperemia. We also tested the hypothesis that coronary flow rate modulates contractility after brief myocardial ischemia, independent of changes in phosphorus metabolites. Eight open-chest pigs were studied with phosphorus-31 nuclear magnetic resonance (NMR) spectroscopy with 14 s time resolution. After a 29-s anterior descending coronary occlusion, peak Doppler coronary flow velocity was alternately unrestricted (normal hyperemia, 443 ± 40% of control) or limited to 159 ± 9% of control. During 29 s coronary occlusion, phosphocreatine-to-inorganic phosphate ratio (PCr/P(i)) and systolic segment shortening in the ischemic region fell to 28 ± 4 and 7 ± 7% of control, respectively. With normal hyperemia, PCr/P(i) and segment shortening recovered within 29 s. With blunted hyperemia, recovery of both parameters was delayed an additional 29-43 s, associated with reduced subendocardial blood flow (measured with radioactive microspheres) and persistent intracellular acidosis. However, the relationship between segment shortening and PCr/P(i) was unaffected by the intensity of reactive hyperemia. Thus blunted reactive hyperemia significantly delays metabolic and contractile recovery from brief ischemia, probably via transient maldistribution of transmural perfusion. However, coronary blood flow rate does not independently modulate contractility after brief reversible ischemia.
KW - Coronary circulation
KW - Energy metabolism
KW - Myocardial contraction
KW - Nuclear magnetic resonance spectroscopy
UR - http://www.scopus.com/inward/record.url?scp=0026074899&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0026074899&partnerID=8YFLogxK
M3 - Article
C2 - 1887933
AN - SCOPUS:0026074899
VL - 261
JO - American Journal of Physiology - Renal Fluid and Electrolyte Physiology
JF - American Journal of Physiology - Renal Fluid and Electrolyte Physiology
SN - 1931-857X
IS - 3 30-3
ER -