Hypertension and the renin-angiotensin system in the congenital hydronephrosis rat with non-obstructive pelviureteric junction abnormalities.

We examined the involvement of the renin-angiotensin system in the maintenance of hypertension of the rat with congenital hydronephrosis having no urinary tract obstruction. The congenital hydronephrosis rat (HNR) had a significantly higher systolic blood pressure (181 +/- 9.5 mm Hg in the male bilateral hydronephrosis rat, BHN, at 13 weeks of age, n = 10) than control Wistar-Imamichi rats (126 +/- 5.8 mm Hg). The plasma renin activity and plasma angiotensin-II concentration of BHN were decreased to 20.1 and 24.6% of those of control rats, respectively. There was a negative correlation between plasma angiotensin-II concentration and blood pressure. In addition, the effect of captopril and indomethacin on the high blood pressure of BHNs was similar to that of human low-renin essential hypertension. These findings suggest that the renin-angiotensin system activity was markedly lowered and that the involvement of the system in the maintenance of hypertension in HNRs is small.