Effect of oral magnesium supplementation on blood pressure, platelet aggregation and calcium handling in deoxycorticosterone acetate induced hypertension in rats.


Kh R, Khullar M, Kashyap M




J Hypertens


OBJECTIVE: To study the effect of oral magnesium supplementation on blood pressure, platelet aggregation and platelet calcium handling in deoxycorticosterone acetate (DOCA)-induced hypertension in rats. DESIGN AND METHODS: Rats were divided into four groups of 20 each. Drug treatments were given for a 6-week period. Control rats were vehicle treated. In the second group, DOCA, 15 mg/kg, was injected subcutaneously twice weekly with 1% NaCl used instead of drinking water. The third group was given magnesium oxide (MgO), 1 g/kg daily, orally by gavage. The fourth group was given MgO along with DOCA and 1% NaCl. Blood pressure and heart rate were measured weekly. Platelet aggregation, intracellular calcium, calcium uptake and calcium efflux studies were performed at the end of sixth week. Serum magnesium concentration, plasma levels of reactive nitrogen intermediates (RNI) and citrulline were also measured RESULTS: There was a significant rise in blood pressure in the DOCA-treated rats. Magnesium prevented the gradual rise in blood pressure when given along with DOCA, but had no effect in normotensive rats. Heart rate did not show any significant change. Platelet aggregation was significantly reduced in all the treatment groups compared to the control group. DOCA treatment produced a significant increase in the intracellular calcium concentration as well as the calcium uptake compared to the control group. Magnesium supplementation inhibited the increased intracellular calcium concentration and calcium uptake in DOCA-treated rats. RNI and citrulline levels were elevated in all the treatment groups. Serum magnesium levels were significantly higher in the magnesium-treated and DOCA plus magnesium-treated rats. CONCLUSIONS: Magnesium supplementation prevents blood pressure elevation in DOCA hypertensive rats. These effects are associated with inhibition of platelet calcium uptake and decreased intracellular free calcium concentration.