THE ROLE OF RENAL HEMODYNAMICS IN THE ANTIHYPERTENSIVE ACTION OF MEPIRODIPINE, A NEW CALCIUM ANTAGONIST

To evaluate the role of regional hemodynamics in the anti-hypertensive effect of mepirodipine, a new dihydropyridine-derivative calcium antagonist, we measured systemic, renal, hepatic, and forearm hemodynamics in 10 patients with essential hypertension treated with mepirodipine (15 mg/day) for 4 weeks. After the administration of mepirodipine, a significant decline in mean blood pressure (-13.8±2.3%, p<0.01) accompanied by a decrease in systemic vascular resistance (-21.1 ± 2.6%, p<0.01) was observed. Although forearm vascular resistance did not change significantly, both renal (-19.2±6.7%, p<0.01) and hepatic vascular resistance (-17.6±3.8%, p<0.01) decreased considerably. The decrements of mean blood pressure with mepirodipine did not correlate with those of hepatic or forearm vascular resistance but correlated positively with those of renal vascular resistance (r=0.699, p<0.05). Moreover, the increment of renal blood flow with mepirodipine was negatively correlated with the pretreatment level of renal blood flow (r=-0.670, p<0.05); renal blood flow increased to a greater extent in patients with lower pretreatment renal blood flow. These findings suggest that the oral administration of mepirodipine in patients with essential hypertension can produce selective vasodilation in the renal vasculature, which may play an important role in the relatively long-term antihypertensive effect of this drug.