Effects of nifedipine on global myocardial ischemic injury in hearts from diabetic and age-matched control rats.

The purpose of this study was to examine the protective activity of a low concentration of nifedipine (3 x 10(-8) M) against global myocardial ischemic injury in isolated perfused hearts from streptozotocin (STZ) diabetic rats (DR) as compared with control rats (CR). Hearts were subjected to 45-min global ischemia followed by 45-min reperfusion. During ischemia, the period of time until onset of the ischemic contracture was significantly longer in hearts from DR than in hearts from CR (20.3 +/- 1.0 and 15.5 +/- 0.5 min, p less than 0.05). The degree of the ischemic contracture was similar in both types of hearts. During reperfusion, a significantly smaller recovery of left ventricular pressure (LVP) was observed as was a tendency for postischemic coronary flow (CF) to be lower in hearts from DR than in those from CR. After pretreatment with nifedipine, the time of onset of the ischemic contracture was significantly more delayed in hearts from DR than in those from CR: from 20.3 +/- 1.0 to 28.1 +/- 1.2 min (p less than 0.05) and from 15.5 +/- 0.6 to 18.1 +/- 0.9 min (p less than 0.05), respectively. In addition, the degree of the ischemic contracture was reduced (45.3%) in hearts from DR but not in those from CR. During reperfusion, the CF was increased only in hearts from DR. No beneficial effects on functional recovery of LVP were observed in either type of hearts, although recovery tended to be better in diabetic hearts. Nifedipine in a low concentration appears to be more effective against myocardial ischemic injury in diabetes, resulting in an improvement in postischemic CF.(ABSTRACT TRUNCATED AT 250 WORDS)