Renin and converting enzyme inhibitors lowered blood pressure in chronic renal hypertensive rats, whereas an angiotensin II antagonist failed to do so.
Do renin-angiotensin system inhibitors lower blood pressure in chronic renal hypertensive rats?
This study demonstrates that in chronic renal hypertensive rats, blood pressure reduction is achievable with renin or converting enzyme inhibitors, but not with angiotensin antagonists, and that volume does not play a major role in maintaining hypertension.
The role of renin-angiotensin system has been examined in the maintenance of hypertension in acute and chronic two-kidney (36 weeks) and chronic one-kidney (12 weeks) Goldblatt hypertensive rats using three inhibitors of this system. The inhibitors used were URI-73A, a synthetic analog of lysophosphatidylethanolamine, which inhibits renin both in vivo and in vitro, SQ14,225, a potent converting enzyme inhibitor, and Sar1, Thr8 angiotensin II, an angiotensin II antagonist. When the inhibitors were administered in acute (high renin) hypertensive rats, they all lowered blood pressure significantly. However, in the chronic (low renin) hypertensive phase, both renin and converting enzyme inhibitors lowered blood pressure, whereas, Sar1, Thr8 failed to lower blood pressure. The renin inhibitor lowered plasma renin activity (PRA), and SQ14,225 and Sar1, Thr8 Ang II increased PRA. Further studies on water and electrolyte balance with one-kidney model hypertensive and uninephrectomized control rats showed no change in plasma volume. However, there was increased 24-hour urinary output and increased sodium excretion. This study indicates that in chronic renal hypertensive rats, blood pressure reduction is possible by either renin on converting enzyme inhibitor, but not by angiotensin antagonists. Since volume did not change either during the development or reversal of hypertension, volume did not appear to play a major role in the maintenance of hypertension.
Sen et al. (1979) studied Chronic renal hypertension. URI-73A, SQ14,225, and [Sar1, Thr8] angiotensin II vs. Uninephrectomized control rats was evaluated on Blood pressure. Renin and converting enzyme inhibitors lowered blood pressure in chronic renal hypertensive rats, whereas an angiotensin II antagonist failed to do so.