Effect of supranormal coronary blood flow on energy metabolism and systolic function of porcine left ventricle.
OBJECTIVE
The goal was to determine if supranormal coronary blood flow increases myocardial oxygen consumption, high energy phosphate levels, and systolic function in the in situ autoperfused heart.


METHODS
Thirteen anaesthetised open chest pigs with an intact, autoperfused coronary circulation, weight 30-40 kg, were studied. Measurements were made under basal conditions and during regional hyperperfusion of the anterior left ventricle produced by intracoronary infusion of adenosine (mean dose 3.3 mumol.min-1). Doppler coronary blood flow velocity in the anterior descending coronary artery, arterial and anterior interventricular venous blood oxygen content, high energy phosphates (by transmurally localised 31P NMR), and myocardial wall thickening (by sonomicrometry) were measured.


RESULTS
With adenosine, coronary flow was increased to 355(SEM 59)% of control. Supranormal coronary flow produced no significant changes in anterior left ventricular oxygen consumption [99(12)% of control]. 31P NMR spectroscopy revealed no significant changes in the peak intensities of phosphocreatine or ATP in either the subendocardium or subepicardium (90-97% of control). Systolic anterior left ventricular wall thickening also did not change [107(13)% of control].


CONCLUSIONS
Supranormal coronary flow does not augment myocardial oxygen consumption, high energy phosphates, or systolic function in the in situ autoperfused heart. Myocardial oxygen delivery does not limit oxidative metabolism under normal conditions.
Schwartz
G G
GG
Department of Medicine (Cardiology Section), San Francisco Veterans Affairs Medical Center.
Schaefer
S
S
Trocha
S D
SD
Garcia
J
J
Steinman
S
S
Massie
B M
BM
Weiner
M W
MW
D000241:Adenosine / Q000494:pharmacology; D000818:Animals; D003331:Coronary Vessels / Q000502:physiology*; D004734:Energy Metabolism / Q000502:physiology*; D005260:Female; D009682:Magnetic Resonance Spectroscopy; D009206:Myocardium / Q000378:metabolism; D010477:Perfusion; D010710:Phosphates / Q000378:metabolism; D012039:Regional Blood Flow / Q000187:drug effects / Q000502:physiology; D013552:Swine; D013599:Systole; D016277:Ventricular Function, Left / Q000502:physiology*
D010710:Phosphates; D000241:Adenosine