Myocardial adenosine formation with increased cardiac performance in the dog

Abstract

Adenosine (Ado) was suggested as a metabolic vasodilator of coronary circulation with a role in matching myocardial O2 supply to myocardial O2 need. Changes in myocardial Ado production, as reflected by changes in the concentration of Ado in a pericardial infusate were evaluated during increased cardiac activity. In anesthetized open-chest dogs, supramaximal stellate ganglion stimulation resulted in pericardial Ado concentrations that were 241 .+-. 21% of control values. Pericardial Ado levels were higher during supramaximal stimulation periods than during control and recovery periods. With supramaximal and graded levels of stellate ganglion stimulation, highly significant linear correlations occurred between hemodynamic parameters and pericardial Ado levels. In unanesthetized dogs, pericardial Ado concentrations during treadmill exercise were 279 .+-. 23% of preexercise control values and a significant linear correlation occurred between pericardial Ado levels and heart rate. Marked increases in pericardial Ado levels during increased cardiac performance in anesthetized and unanesthetized animals and the apparent correlations between levels of Ado production and levels of cardiac activity, are supportive evidence for a role for Ado in matching myocardial O2 supply to myocardial O2 need under physiological conditions.