[The effects of nifedipine on blood pressure and renal function]

The effects of nifedipine (NIF) on blood pressure and renal function were examined in control spontaneously hypertensive rats (SHR) (group A), SHR with moderate renal dysfunction (group B), and those with severe renal dysfunction (group C). The hypotensive effect of NIF administration was greater in SHR with severe renal dysfunction, and this might relate with pharmacokinetics of NIF, decreased sensitivity of baroreflex and low plasma renin activity in SHR with reduced renal function. When mean arterial blood pressure (MAP) was reduced by about 30% in these three groups, the baseline renal function was maintained and natriuresis was observed in group A and B, whereas the renal function and urine volume decreased transiently, and urinary sodium excretion tended to decrease in group C. In hypertensive patients with normal renal function (group I), moderate renal dysfunction (group II), and severe renal dysfunction (group III), 5 or 10 mg NIF was orally administered. In these three groups, MAP was reduced by about 20%. In group I, glomerular filtration rate tended to increase, renal plasma flow increased and natriuresis was observed. In group II and III, renal function didn't decrease with few exception, but when MAP was reduced by about 30%, renal function decreased in three of five cases. Also on long-term administration of NIF in hypertensive patients, renal function improved. The results suggests that NIF by single administration or long-term administration is effective on hypertensive patients with renal dysfunction, but we should be cautious to decide the dose of NIF and the rate of blood pressure reduction.