Weinstock M, Borosh M, Kafri O, Kaczmarczyk G
Department of Pharmacology, Hebrew University-Hadassah Medical School, Jerusalem, Israel.
J Hypertens. 1991 Sep;9(9):799-804. doi: 10.1097/00004872-199109000-00005.
This study determined the influence of baroreflex sensitivity (BRS) on the rate of urinary sodium excretion and plasma renin activity (PRA) in response to a saline infusion in conscious male rabbits specifically bred for high (Group I; n = 7) and low (Group II; n = 10) BRS and in seven control animals. Only Group II showed significant increases in blood pressure on a chronic high-salt intake. After ensuring that each animal was in sodium balance, a (0.7-0.9%) saline infusion of 3-4 ml/kg per h for 90 min (25% daily sodium intake for each rabbit) was given and urine collected at 15-min intervals via a bladder catheter. No differences were found in control urine volumes, urinary sodium or PRA. Group I excreted over 50% of the sodium load and Group II less than 20% within 90 min. PRA fell by more than 30% within 30 min in six Group I rabbits but decreased by less than 30% or increased in Group II. In the control animals, sodium excretion rates and PRA suppression were also much greater in those with high BRS. A highly significant correlation (r = 0.808, P less than 0.01) was found between the per cent of the sodium load excreted and BRS. It is suggested that the delayed sodium excretion and blood pressure elevation in salt-sensitive subjects may be due to a genetic impairment in baroreflex control of renal sympathetic nerve activity.
本研究测定了压力反射敏感性（BRS）对特意培育的高BRS（I组；n = 7）和低BRS（II组；n = 10）雄性清醒家兔以及7只对照动物在输注生理盐水时尿钠排泄率和血浆肾素活性（PRA）的影响。只有II组在慢性高盐摄入时血压有显著升高。在确保每只动物钠平衡后，以3 - 4 ml/kg每小时的速度输注（0.7 - 0.9%）生理盐水90分钟（相当于每只兔子每日钠摄入量的25%），并通过膀胱导管每隔15分钟收集尿液。对照尿量、尿钠或PRA未发现差异。I组在90分钟内排泄了超过50%的钠负荷，而II组排泄少于20%。I组6只兔子的PRA在30分钟内下降超过30%，而II组下降少于30%或升高。在对照动物中，高BRS的动物钠排泄率和PRA抑制也更大。钠负荷排泄百分比与BRS之间存在高度显著的相关性（r = 0.808，P < 0.01）。提示盐敏感受试者钠排泄延迟和血压升高可能是由于肾交感神经活动的压力反射控制存在基因缺陷。
