EFFECTS OF SHORT-TERM TREATMENT WITH TRAN DOLAPRIL ON AGONISTS-INDUCED AND FLOW-INDUCED RELAXATIONS IN SHR CORONARY-ARTERIES

The aim of the study was to assess the effects of a-one-month treatmen t period with the ACE inhibitor trandolapril (0.3 mg/kg/day) on the en dothelial reactivity in epicardial right coronary arteries (CA) of 26- 30 week-old SHRs. For this purpose, segments of CA were mounted in an arteriograph where wall thickness and internal diameter (ID) were cont inuously monitored while intraluminal pressure (IF) was controlled. In the absence of flow and under an IP of 30 mmHg, IDs were not signific antly different in control compared to those of treated SHR arteries ( mu m, 250 +/- 8 vs 240 +/- 7). In preconstricted preparations (5HT, 10 mu m extraluminally) C/E curves were constructed by adding acetylchol ine (AC, 0.01-10 mu M) or bradykinin (BK, 0.01-10 mu M) in the bath. O n the other hand, the effect of a stepwise increase in intraluminal fl ow (50-450 mu l/min; IP = 30 mmHg) of perfusion solution was observed. The effects of subsequent additions of sodium nitroprusside (SNP) wer e assessed. Maximal relaxations were expressed as percent of maximal c ontractions. Results were as follows : [GRAPHICS] These results show t hat the endothelium-dependent relaxation induced by AC and BK were sig nificantly increased in coronary arteries of treated compared to contr ol SHRs whereas the flow-induced relaxation seemed to remain unaffecte d in our experimental conditions. From these data, it can be concluded that a short period of ACE inhibition in SHRs is able to improve the endothelium-dependent vasodilation induced by agonists in the coronary arterial bed.