The effects of myocardial ischemia followed by reperfusion on perfused coronary capillarity.

ABSTRACT

To determine the effects of ischemia and reperfusion on myocardial perfused capillary density, rat hearts were excised, kept ischemic for thirty minutes then reperfused with blood from a support animal. Control hearts were isolated and perfused for either 10 or 60 minutes before injection of a vascular marker (Monastral Blue-blood mixture, 30 sec at 100 mmHg). The ischemic hearts were perfused with Blue after 10 minutes of reperfusion. The perfused capillary density (theta) and capillary/fiber ratio (C/F) were measured from frozen transverse sections of the left ventricle. For 10- and 60-minute control hearts, the epicardial theta values were 2324 +/- 476 caps/mm2 and 2378 +/- 330 SD. The endo/epi theta ratio was not significantly less than unity for either control group. For the ischemic group, theta was significantly decreased both in the epicardium (707 +/- 515 caps/mm2) and endocardium (130 +/- 30 caps/mm2) (p less than 0.05). The endo/epi theta ratio was significantly less than unity for the ischemic group (P less than 0.05). The C/F ratio analysis yielded the same results. The decrease in both theta and CF ratio indicate that 30 minutes of ischemia followed by 10 minutes of reperfusion caused a marked "No-reflow" phenomena in isolated, supported hearts. The No-reflow was most pronounced in the endocardium.