EFFECT OF MAGNESIUM-SULFATE ADMINISTRATION ON SUBENDOCARDIAL AND SUBEPICARDIAL PERFUSION

The objective of this study was to determine the effect of systemic Mg SO4 infusion on subendocardial and subepicardial perfusion. Seventeen spontaneously breathing piglets were examined. Myocardial perfusion wa s measured using radiolabeled microspheres at baseline, 30 and 60 min after either MgSO4 (80 mg/kg) or saline infusion. Blood pressure, hear t rate, and cardiac output were also measured at these time intervals. Comparison of the magnesium-induced changes in systemic blood pressur e and on subendocardial and subepicardial perfusion at 30 and 60 min w ith values obtained with saline solution at 30 and 60 min,yielded no s tatistically significant difference (Tables 1-3). The ratio of subendo cardial/subepicardial blood now and subendocardial and subepicardial c oronary vascular resistance at 30 and 60 min revealed no statistically significant differences between the magnesium and the control group ( Table 3). There were no statistically significant difference in cardia c output and heart rate during any of the measured periods (Table 2). Our results suggest that the administration of MgSO4 does not alter th e ratio of subendocardial/subepicardial blood flow and the ratio of su bendocardial/subepicardial coronary vascular resistance.