EFFECT OF ANGIOTENSIN-CONVERTING ENZYME-INHIBITORS ON RESISTANCE ARTERY STRUCTURE AND ENDOTHELIUM-DEPENDENT RELAXATION IN 2-KIDNEY, ONE-CLIP GOLDBLATT HYPERTENSIVE AND SHAM-OPERATED RATS

1. This study was designed to examine the effect of angiotensin-conver ting enzyme inhibitors on resistance artery structure and endothelium- dependent relaxation in Goldblatt two-kidney, one-clip hypertensive ra ts, Four weeks after clipping, hypertensive and sham rats were treated with either perindopril (1 mg day(-1) kg(-1)) or quinapril (3 or 30 m g day(-1) kg(-1)). After 6 weeks mesenteric resistance arteries were m ounted in a myograph for measurements of vascular structure, The endot helium-dependent relaxation response to acetylcholine and bradykinin a nd the response to the nitric oxide donor sodium nitroprusside were re corded. 2. All treatment regimes lowered the blood pressure and revers ed both cardiac and resistance artery hypertrophy. Two-kidney, one-cli p rats treated with quinapril showed a dose-dependent reduction in med ia cross-sectional area and media to lumen ratio. 3. Hypertension of 1 0 weeks' duration was associated with an impaired endothelium-dependen t relaxation response to acetylcholine and bradykinin. Treatment with perindopril and either dose of quinapril prevented the development of impaired endothelium-dependent relaxation but had no effect on the res ponse to sodium nitroprusside, Treatment had no effect on endothelium- dependent relaxation in sham rats. 4. Angiotensin-converting enzyme in hibitor treatment is effective in normalizing blood pressure and cardi ovascular structural changes, Angiotensin-converting enzyme inhibitor treatment prevented the development of impaired endothelium-dependent relaxation to both acetylcholine and bradykinin. The ability of angiot ensin-converting enzyme inhibitors to reverse cardiovascular structura l changes and prevent the development of abnormal endothelium-dependen t relaxation may contribute to the overall effect of this type of anti hypertensive drug.