Relationship of cardiac oxygen usage, adenosine content, and coronary resistance in dogs.
Analysis of the relationships between cardiac oxygen usage (MVO2), cardiac muscle adenosine levels([Ado]), and coronary vascular resistance (R) in open-chest, anesthetized dogs tested the hypothesis that adenosine is a physiological regulator of coronary flow. Experiments using each dog as its own control showed that [Ado] varied directly with MVO2 as the latter changed spontaneously or in response to atrial pacing, paired pacing, aortic constriction, of beta-adrenergic blockade. In turn, R varied inversely with changes in [Ado]. Stimulating MVO2 with isoproterenol significantly increased the slope of the regression of [Ado] on MVO2 as well as of R-1 on [Ado]. The effect of beta-adrenergic stimulation on [Ado] is unexplained, but its effect on R-1 seems to reflect the combined effects of adenosine and direct beta-adrenergic coronary relaxation. These results support the hypothesis that adenosine mediates the coronary flow responses to changes in MVO2.
D000241:Adenosine / Q000502:physiology; D000818:Animals; D004285:Dogs; D005260:Female; D006339:Heart Rate; D008297:Male; D009132:Muscles / Q000032:analysis; D009200:Myocardial Contraction; D009206:Myocardium / Q000378:metabolism*; D010100:Oxygen / Q000502:physiology*; D010477:Perfusion; D014655:Vascular Resistance
D000241:Adenosine; D010100:Oxygen