Opposite Effects of Calcium and Magnesium on the Central Blood Pressure Regulation in the Spontaneously Hypertensive Rats

The effects of intracerebroventricular administration of calcium or magnesium on the blood pressure regulation in the brain were investigated. The systolic blood pressure in spontaneously hypertensive rats (male, 13-week-old) was decreased by calcium chloride (100 μg/rat) and increased by magnesium chloride (20, 100 or 500 μg/rat). The depressor response induced by calcium was inhibited by magnesium chloride in a dose-dependent manner. Combining these results with those previously reported, it is suggested that magnesium inhibits the ability of calcium to reduce blood pressure through calmodulin- and dopamine-dependent functions in the brain.