P4.09 DIFFERENT EFFECTS OF 7-NITROINDAZOLE AND L-NAME ADMINISTERED INDIVIDUALLY AND/OR TOGETHER ON CARDIOVASCULAR SYSTEM OF ADULT WISTAR RATS

Abstract

Objectives: We evaluate the effect of NG-nitro-L-arginine methylester (L-NAME) and 7-nitroindazole (7NI) administered individually and/or together on cardiovascular system of adult Wistar rats. Methods: L-NAME (50 mg/kg/day in tap water) and 7NI (10 mg/kg/day in pellets) was administered to Wistar rats from 10th–16th week of age. Blood pressure (BP) was measured by the plethysmographic method weekly. For morphological study the animals (n=10 in each group) were perfused with a fixative (120 mmHg) and carotid and coronary arteries were processed for electron microscopy. For functional investigation aortal rings (n=10 in each group) in organ bath were used. Results: L-NAME administration to Wistar rats evoked increase of BP, hypertrophy of the heart and arterial wall, increase of cross sectional areas (CSA) of endothelial and muscle cells, increase of extracellular matrix, decrease of endothelial dependent relaxation (EDR) to acetylcholine, and increase of noradrenaline contraction. 7NI administration resulted in BP independent hypotrophy of the heart and arterial wall, decrease CSA of endothelial and muscle cells without affecting CSA of extracellular matrix, mild decrease of acetylcholine induced EDR, and noradrenaline contraction. Common administration of 7NI and L-NAME evoked (i) lower effect on BP, and trophicity of both arteries and heart compared to L-NAME, and (ii), similar decrease of EDR as in L-NAME group, and (iii) decreased contractile effect. Conclusions: The results indicate that two different NO-synthase inhibitors L-NAME and 7NI via decreased synthesis of the same NO molecule evoked different and in many causes the opposite effects on cardiovascular system of normotensive Wistar rats. P4.10 Withdrawn by author