AJP - Heart and Circulatory Physiology, Vol 243, Issue 3 480-H487, Copyright © 1982 by American Physiological Society
Effect of aminophylline on coronary functional hyperemia and myocardial adenosine
C. E. Jones, T. W. Hurst and J. R. Randall
The role of adenosine in coronary functional hyperemia was tested using the
adenosine antagonist aminophylline. In 11 dogs left coronary blood flow
(LCBF) and left ventricular oxygen extraction [(a-v)O2] were monitored.
Myocardial oxygen consumption (MVO2) was calculated. Before aminophylline
was administered, intracoronary infusion of 6.8 micrograms/min
norepinephrine increased LCBF and MVO2 by 40-80%. Simultaneous infusion of
adenosine further increased LCBF. Fifteen minutes after injection of 100 mg
aminophylline, norepinephrine still increased LCBF, and the ratio delta
LCBF/delta MVO2 was unchanged (P greater than 0.05). Although the
functional hyperemia was not blunted, the response to infused adenosine was
abolished by aminophylline. In 20 additional dogs myocardial adenosine was
determined. Before norepinephrine infusion myocardial adenosine with and
without aminophylline was 12.7 and 14.3 nmol/g dry wt, respectively (P
greater than 0.05). During norepinephrine infusion an increase in adenosine
correlated well with increases in MVO2 and LCBF, but the increase in
adenosine was not greater after aminophylline. Thus the failure of
aminophylline to blunt functional hyperemia was not due to a higher
adenosine level after aminophylline. These results do not support a role
for adenosine in functional hyperemia elicited by norepinephrine.
