Abstract:
Aim\ To investigate the chronic effect of captopril treatment on circulating and tissue renin-angiotensin system(RAS) in relation to left ventricular hypertrophy and blood pressure.\ Methods\ Male spontaneously hypertensive rates(SHR) were given captopril 100 mg·kg -1 ·d -1 (SHRcap n=43) from intrautero period to 16 weeks(wks) of age, then the treatment was removed.\ Rats were killed at 16(n=19) and 40(n=24) wks of age respectively.\ Male,agematched untreated SHR and WistarKyoto(WKY) rats served as controls.\ Systolic blood pressure(SBP), left ventricular mass/body weight(LVM/BW) ratio were determined.\ Left ventricular(LV) myocardium and plasma angiotensin Ⅱ(AngⅡ) concentration were assessed by radioimmunoassay.\ Aortic and serum angiotensin converting enzyme(ACE) activity were measured by spectrophotometric method.\ Angiotensinogen(AGT) mRNA level in kidney and liver, renal renin mRNA level were determined using Northern blot.\ Results\ Early captopril treatment significantly decreased SBP(mmHg:158±11 vs untreated SHR 216±12,P<005) and LVM/BW(mg/g:256±022 vs untreated SHR 355±023, P<005) at 16 wks of age, and the effect remained to 40 wks of age(SBP mmHg:173±10 vs untreated SHR 232±16 P<005; LVM/BW mg/g: 287±023 vs untreated SHR 375±052, P<005).\ Captopril therapy did not affect BW, plasma AngⅡ concentration, serum ACE activity and AGT mRNA in liver, but markedly reduced LV myocardium AngⅡ concentration at 40 wks of age(pg/100 mg: 263±64 vs untreated SHR 316±62, P<005), inhibited aortic ACE activity at 16 wks(U/100 g:46±15 vs untreated SHR 63±21, P<005) and 40 wks of age(U/100 g:71±16 vs untreated SHR 94±23, P<005); reduced 465%~511% AGT mRNA level in kidney of 16 wks and 40 wks SHR.\ Conclusion\ AGT mRNA in kidney, LV myocardium AngⅡ and aortic ACE activity, rather than AGT mRNA in liver, renin mRNA in kidney, plasma AngⅡ and serum ACE activity, could be inhibited by longterm captopril treatment, and it may play a role in the mechanisms of the persistent antihypertensive effect and preventive effect of LVH of captopril.