Studies of the hypotensive effect of calcium injected into lateral brain ventricles.

Calcium chloride (1-2 mumole) injected into lateral brain ventricles of pentobarbital anesthetized rats markedly decreases blood pressure. The hypotensive response is not affected by vagotomy and is characteristic calcium and barium since other polyvalent cations do not have the same effect. The calcium channel blocker, verapamil given into brain ventricles prevents the depressor effect of calcium suggesting that the hypotensive action of calcium is initiated intracellularly. The well documented lowering of blood pressure by increases in dietary intake of calcium may be mediated by increases in free calcium in cerebrospinal fluid.