T. Minamino et al., EFFECTS OF ISCHEMIC PRECONDITIONING ON CONTRACTILE AND METABOLIC FUNCTION DURING HYPOPERFUSION IN DOGS, American journal of physiology. Heart and circulatory physiology, 43(2), 1998, pp. 684-693
We examined the effects of ischemic preconditioning (IP) on metabolic
and contractile function during coronary hypoperfusion in dogs. After
the left anterior descending coronary artery (LAD) was occluded for 5
min (IP) and reperfused for 10 min, coronary blood Bow (CBF) of the LA
D was decreased to 33% of the control. IP increased (P < 0.05) lactate
extraction ratio and the pH of coronary venous blood and decreased (P
< 0.05) myocardial oxygen consumption and fractional shortening durin
g hypoperfusion compared with those in the control group, although IP
did not change the endocardial-to-epicardial blood flow rai;io of the
regional myocardium during hypoperfusion. IP increased (P < 0.115) the
adenosine levels in coronary venous blood during hypoperfusion. IP in
creased (P < 0.05) myocardial ecto-5'-nucleotidase activity. Administr
ation of 8-sulophenyltheophylline or alpha,beta-methyleneadenosine 6'-
diphosphate blunted the IP-induced changes in metabolic and contractil
e parameters during hypoperfusion. These results suggest that IP reduc
ed the severity of anaerobic myo-cardial metabolism of ischemic hearts
by increasing the adenosine levels via an extracellular pathway.