Abstract
The vasoconstrictor responses to electrical nerve stimulation or exogenous norepinephrine as well as endogenous norepinephrine overflow from the adrenergic nerve endings in the isolated mesenteric vasculatures were significantly increased in young SHR (7-8W) compared with their age-matched WKY. On the other hand, basal plasma norepinephrine and its responses to 20 minutes-standing were significantly increased in WHO stage I essential hypertension than those in the normotensive controls and in WHO stage II essential hypertension.
Ca-induced reduction of osmotic fragility of erythrocyte, determined by Coil Planet Centrifuge System, and of erythrocyte membrane fluidity, determined by electron spin resonance method, was more prominent in essential hypertension and SHR compared with that in their normotensive controls.
These results suggest that genetic abnormalities of physicochemical properties or Ca-sensitivity of the membranes could induce an exaggerated sympathetic nerve activity and vascular reactivity and contribute, at least partially, to the pathogenesis of hypertension in SHR and essential hypertension.
