MECANISMES D'ACTION POSSIBLES DU POTASSIUM DANS L'HYPERTENSION ARTERIELLE

Potassium supplementation of the diet attenuates the rise in blood pressure in stroke prone spontaneously hypertensive rats (SHRSP) without a concomitant contraction of intravascular volume. This finding favours a resistance-mediated, but not a volume-mediated hypotensive action of potassium. A possible site of effect is modulation of sympathetically mediated vasoconstriction by potassium. Sympathetic vascular tone, which is enhanced in SHRSP on a high sodium diet because of a reduced noradrenaline inactivation, a facilitated noradrenaline release and an increased sensitivity of vascular smooth muscle to noradrenaline, tends to normalize when the potassium content of the diet is augmented. All three parameters of sympathetically mediated vasoconstriction are altered by potassium in a way to attenuate the enhanced sympathetic vasoconstriction.