HYPERTENSION AND THE RENIN-ANGIOTENSIN SYSTEM IN THE CONGENITAL HYDRONEPHROSIS RAT WITH NONOBSTRUCTIVE PELVIURETERIC JUNCTION ABNORMALITIES

We examined the involvement of the renin-angiotensin system in the mai ntenance of hypertension of the rat with congenital hydronephrosis hav ing no urinary tract obstruction. The congenital hydronephrosis rat (H NR) 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 pl asma renin activity and plasma angiotensin-II concentration of BHN wer e decreased to 20.1 and 24.6% of those of control rats, respectively. There was a negative correlation between plasma angiotensin-II concent ration and blood pressure. In addition, the effect of captopril and in domethacin on the high blood pressure of BHNs was similar to that of h uman low-renin essential hypertension, These findings suggest that the renin-angiotensin system activity was markedly lowered and that the i nvolvement of the system in the maintenance of hypertension in HNRs is small.