Effects of Nicardipine and Sodium Nitroprusside on Functional Recovery of Stunned Myocardium in Dogs

Yoo, Kyung Yeon; Na, Jae Hyeong; Im, Woong Mo

Abstract

BACKGROUND: Cytosolic Ca2+ overload and oxygen derived free radicals may contribute to stunned myocardium. The pnt study was aimed to investigate the effects of nicardipine and sodium nitroprusside (SNP) on the functional recovery of postischemic reperfused myocardium.
METHODS
Fifty-seven halothane-anesthetized dogs were subjected to 15 minutes of 1eft anterior descending coronary artery (LAD) occlusion and 3 hours of reperfusion. They were randomly assigned to receive either intracoronary nicardipine (n=11) or SNP (n=10) alone or both (nicardipine plus SNP, n=10). Eleven dogs that received saline i.c. served as the controL Regional myocardial contractility was evaluated by systolic shortening (%SS), the preload recruitable stroke work slope (Mw), and intramyocardial pressure (IMPs). Diastolic function was assessed by time constant of myocardial relaxation (IMP-tau) and postsystolic shortening (%PSS), LAD blood flow was measured by a Doppler flowmeter as well.
RESULTS
LAD occlusion produced a significant reduction in systolic as well as diasto1ic functions to similar degrees in all groups. However, %SS was significantly higher in the nicardipine, SNP and nicardipine-SNP groups (67%, 56%, and 68% of baseline values, respectively) than in the controls (20%) at 3 hours of reperfusion. Furthermore, Mw recovered to the baseline with the onset of reperfusian in the three experimental groups. IMP-tau was restored to the baseline during early nperfusion in the SNP-treated groups but was significantly prolonged in the control and nicardipine poups throughout the seperfusion. LAD blood flow during reperfusion was higher in the SNP-treated groups in comparison to the control group.
CONCLUSIONS
Treatment with either nicardipine or SNP enhances the recovery of mgional contractile function in the canine model of myocardial stunning. SNP not nicardipine is also beneficial in attenuation of early diastolic dysfunction. Nicardipine combined with SNP improved systolic as well as early diastolic functions more significantly when compared to either nicardipine or SNP alane.