Does early captopril treatment and its removal affect plasma ACE activity and AVP levels in hypertensive and normotensive rats?
In spontaneously hypertensive rats, captopril treatment decreases plasma AVP levels, which may contribute to its antihypertensive mechanism of action despite an increase in plasma ACE activity.
The purpose of this study was to evaluate the effects of early administration and removal of the ACE inhibitor, captopril (CAP) on the plasma ACE activity, AVP levels, and mean arterial pressure (MAP) in groups of rats, control and CAP treated SHR and WKY (SHR, WKY SHRCAP, WKYCAP, respectively and in SHR taken off CAP (OFFCAP) and their progeny (2nd generation, 2ndG). Plasma ACE activity in SHRCAP (54.8 +/- 2.1 mU/ml/min) was significantly greater than in SHR (25.96 +/- 0.34 mU/ml/min) and their offspring (OFFCAP, 26.32 +/- 2.71 and 2ndG, 17.62 +/- 2.47 mU/ml/min, P < 0.001, respectively). Plasma level of AVP in SHR (14.18 +/- 0.98 pg/ml) were greater than in SHRCAP (9.1 +/- 1.01 pg/ml, P < 0.01). A decrease in plasma AVP levels were also noted in OFFCAP (10.48 +/- 0.51 pg/ml) and their offspring 2ndG (10.34 +/- 0.46 pg/ml). Our results did not show a relationship between plasma ACE activity and blood pressure reduction. However, treatment of SHR with captopril produced a decrease in plasma AVP levels which may participate in its antihypertensive mechanism of action.
Zhang et al. (Mon,) studied this question.
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