Dietary potassium, blood pressure and peripheral adrenergic responsiveness in the deoxycorticosterone acetate-salt rat.

This study investigated the effect of 6 weeks of dietary potassium (K) supplementation on blood pressure and in vivo and in vitro peripheral adrenergic responsiveness in deoxycorticosterone acetate (DOCA)-salt hypertensive rats. Dietary K supplementation did not affect the development of hypertension in DOCA-salt rats. The chronotropic and dipsogenic responses to isoproterenol (ISO) administration were significantly decreased in DOCA-salt rats. Addition of K to the diet resulted in a complete normalization of both of these responses so that they were similar to controls. Aortic smooth muscle from DOCA-salt rats exhibited a significant reduction in the relaxation response to ISO. Dietary K supplementation resulted in only a partial normalization of this response. Enhanced norepinephrine responsiveness was observed in aortic smooth muscle from DOCA-salt rats, but was not affected by dietary K supplementation. These results show that: 1) a 0.5% dietary K supplementation in DOCA-salt rats does not prevent the development of hypertension, 2) the decreased peripheral beta-adrenergic responsiveness observed in DOCA-salt rats is partially normalized by the addition of K to the diet, and 3) the increased alpha- adrenergic sensitivity is not affected by the 0.5% dietary K supplementation in the DOCA-salt rat. It is concluded that dietary K supplementation has differential effects on peripheral alpha- and beta- adrenergic responsiveness in the DOCA-salt rat. These actions may be related to the lack of an antihypertensive effect of K in the present study.