Effects of lisinopril and amlodipine on antioxidant status in experimentalhypertension

The objective of this investigation was to compare changes in antioxidant s tatus (together with other metabolites relevant to hypertension) in plasma and cardiac tissue from spontaneously hypertensive rats (SHR) and normotens ive Wistar Kyoto rats (WKY), following 8 weeks of treatment with lisinopril (angiotensin converting enzyme inhibitor) or amlodipine (Ca2+ channel anta gonist) respectively. There was no significant difference in the levels of total antioxidant capacity, retinol, urea, albumin or triglyceride in plasm a from SHR or WKY rats, with or without lisinopril or amlodipine treatment. However in SHR rats, levels of alpha-tocopherol were substantially reduced in both plasma (-54% WKY, P < 0.01) and cardiac tissue (-43% WKY, P < 0.05 ). Treatment with lisinopril ameliorated reduced levels of plasma alpha-toc opherol in SHR rats, but not in cardiac tissue. Amlodipine treatment had no effect on alpha-tocopherol levels in plasma or cardiac tissue in SHR rats. in SHR rats total cholesterol levels were significantly lower than WKY con trols (-36%, P < 0.001). This effect was reversed in lisinopril treated SHR rats (+27%, P < 0.01). Plasma high density lipoprotein (HDL) and low densi ty lipoprotein (LDL) cholesterol were reduced in untreated SHR rats (P < 0. 025) when compared to WKY controls, neither lisinopril nor amlodipine treat ment significantly altered these parameters. These findings suggest possibl e alternative mechanisms of action for lisinopril, and reinforce its use in hypertensive patients or patients with left ventricular hypertrophy. (C) 2 000 Elsevier Science B.V. All rights reserved.