Adrenal regeneration
hypertension was induced in male Wistar rats by unilateral adrenal enucleation, contralateral
adrenalectomy and the provision of a 1% (w/v) NaCl
solution for drinking. A fivefold increase in dietary KCl content caused a significant reduction in the systolic blood pressure of hypertensive rats but not of control rats. During the increase in
potassium intake there was a marked
polydipsia. When 1% NaCl
solution was the drinking fluid, the resultant increase in
sodium intake was associated with an abolition of the
antihypertensive effect of
potassium loading, but when the
sodium intake was held constant, the
antihypertensive effect was maintained. In rats with adrenal regeneration
hypertension, plasma volume was significantly higher, and packed cell volume and
plasma protein concentrations were significantly lower than in control rats. These differences were abolished after 4 days of dietary KCl supplementation. Increased
dietary potassium intake was associated with significantly lower serum
aldosterone concentrations and significantly higher plasma
potassium concentrations in adrenal enucleated rats compared with controls. The possibility that a reduction in extracellular fluid volume (due to a natriuresis) and/or a peripheral vasodilatation contributed to the
antihypertensive effect of KCl loading is discussed.