Breakdown of Blood–Cerebrospinal Fluid Barrier for Calcium Ions in the Absence of Glucocorticoids

Abstract

RABBITS become extremely susceptible to intravenous infusion of a solution of calcium chloride after adrenalectomy (our unpublished work). Unlike the intact animals, adrenalectomized rabbits easily succumb to shock, before cardiac disturbances caused by an enormous elevation of serum calcium content. Myosis and slight bradycardia appear at first, then cyanosis and a progressive decline in blood pressure follow. These symptoms were found to be quite similar to those induced by intracisternal injection of small amounts of calcium chloride solution in this animal species and could be prevented by pretreatment with glucocorticoids. We have therefore examined whether the increased susceptibility of adrenalectomized rabbits to the elevation of serum calcium content is caused by an increase in permeability of the blood–cerebrospinal fluid barrier or by an increased central susceptibility to a small increment in the concentration of calcium in the cerebrospinal fluid.