MODULATION OF CEREBRAL CALCIUM HOMEOSTASIS IN RATS BY ANGIOTENSIN-II IN-VIVO

The uptake of Ca-45(2+) by different regions of the brain was determin ed in anaesthetised rat after infusing angiotensin II (AII; 14 mu g in 1 ml) through the carotid artery. The control animals (C) were infuse d with physiological saline. Ca-45(2+) was injected in the tail vein 2 min after the infusion of AII or saline. Plasma radioactivity was mon itored until euthanasia at different times post injection when the cer ebral uptake of Ca-45(2+) was determined. While the plasma turnover of Ca-45(2+) was similar in AII and C animals, the uptake was markedly h igher in AII vs. C at the different brain sites at all times. Kinetic analysis suggested that AII induced a short term increase in Ca2+ tran sport across the blood-brain barrier and also in the cellular uptake. The effect of AII was receptor mediated being abolished by saralasin, an AII antagonist, and appeared to be at least in part independent of its presser effect. (C) 1997 Elsevier Science Ireland Ltd.