DIETARY CALCIUM SUPPLEMENTATION AND DOPAMINE-BETA-HYDROXYLASE IN SPONTANEOUSLY HYPERTENSIVE RATS

Spontaneously hypertensive 4-week-old male rats were fed, before and a fter the onset of hypertension, with either commercial chow (control) or commercial chow combined with different forms of mirk proteins with or without calcium supplementation. After 40 weeks, rats were still h ypertensive, and dopamine-beta-hydroxylase enzyme activity measured si multaneously in serum and adrenal was found to be higher than in the c ontrols. The enzyme activity in rats fed diets with milk proteins was increased significantly in both serum and adrenal compared with the co ntrol, and such enhancement was significantly higher than that observe d in animals fed the commercial diet supplemented with calcium (1.2%), suggesting that dietary calcium intake associated with dietary protei n of high digestibility, such as casein, potentiates the endogenous me chanisms regulating the homeostasis of calcium more than calcium suppl ementation itself Moreover, the selective and additive effect of diets supplemented with milk proteins and calcium on adrenal enzyme activit y clearly suggests a relationship between cardiovascular diseases invo lving the genesis of hypertension and stress mechanisms through the hy pothalamo-pituitary adreno sympathetic axis. (C) 1997 Elsevier Science Inc.