Abstract
The effect of synthetic angiotensin II (Hypertensin, CIBA) on renal pressor activity and functional renal mass was studied in the rats which had been made hypertensive by main renal artery constriction associated with contralateral nephrectomy. Uninephrectomized rats served as controls. Angiotensin (10μg, per day) suspended in 0.2ml of sesame oil was subcutaneously injected for 6 days after hypertension had been well established. The rats were divided into four groups; Group I (6 rats): uninephrectomy+oil, Group II (8 rats): uninephrectomy+angiotensin in oil, Group III (9 rats): renal artery clipping+oil, and Group IV (8 rats): renal artery clipping+angiotensin in oil. When the animals were sacrificed, the kidney was weighed and processed for determining its pressor activity (renin content) and juxtaglomerular granular index (JGI).
Kidney weight/body weight (%) was 0.88±0.051, 0.84±0.047, 0.75±0.052, and 0.93±0.057 (mean±SE), for Groups I, II, III, and IV, respectively. Difference in the values between Groups III and IV was statistically significant (P<0.05). Renin content for Groups I-IV was 20.4±3.1, 24.5±3.2, 21.4±4.8, and 7.9±2.2ng/ml equivalent to angiotensin II, respectively. JGI for each group was 18.8±2.8, 17.0±1.2, 16.6±2.1, and 7.3±1.2, respectively. Both renin content and JGI were not substantially different among Groups I and II or III, and they were significantly lower in Group IV than in Group III. From these findings, it was concluded that angiotensin produced a marked increase in functional renal mass concomitant with adecrease in renal pressor activity of hypertensive rats. But the effects of angiotensin were not observed in the controls.
