Endotheiium-dependent and independent relaxation effects on aorta preparations of renal hypertensive rats

Abstract

AbstractThe important role of the endothelium in the effects of many vasodilating substances has been amply demonstrated (for review: Furchgott, 1983). Thus, acetylcholine and histamine produce relaxation of pre-contracted (norepinephrine 107 M) rat aorta preparations only in the presence of intact endothelial structures (Van DE Voorde & Leusen, 1983). In a previous study we demonstrated that these endotheiium-dependent responses were much less pronounced in aorta rings of renal hypertensive rats than in aorta preparations of normotensive rats (Van DE Voorde et al., 1984). Impaired relaxation responses were also reported (Cohen & Berkowitz, 1976) to substances which are thought to act directly on the smooth muscle cells (e.g. isoproterenol, nitroglycerine). Microscopic examination of the hypertensive preparations revealed, however, important histologic changes not only in the muscular cell layer of the vessel wall but also in the intima. These observations led us to investigate whether the impaired relaxa...