[A preliminary study on the cellular mechanism of hypotensive effect of high calcium diet in spontaneously hypertensive rats].

Significant reduction of both systolic blood pressure and body weight could be observed in SHRs after being fed with high calcium diet for about 7 weeks (P less than 0.01), with some changes of characteristics in ion transport in RBCs. The intracellular content of Na+, K+, the basic and calmodulin-stimulated activity of calcium-pump, and the calcium membrane binding ability on RBCs in SHR were determined. The intracellular content of K+ and the calmodulin-stimulated activity of calcium-pump in SHR fed with high calcium diet were significantly higher than those in SHR fed with normal calcium diet (P less than 0.01). The ratio of intracellular Na+ to K+ and the calcium membrane binding ability were found to be significantly reduced in SHR fed with high calcium diet (P less than 0.05). The systolic blood pressure in SHR fed with high calcium diet was found to be correlated inversely with the calmodulin-stimulated activity of calcium-pump and the intracellular K+ content (r = -0.720, r = -0.663 respectively, P less than 0.01). Thus, the hypotensive effect of chronic high calcium diet may be mediated through the changes in plasma ion transport, which most likely resulted from the changes in composition and structure of plasma membrane. The exact mechanism concerning the reduced calcium membrane binding ability in SHR fed with high calcium diet still remained unknown.