ARECOLINE STIMULATION OF RADIOLABELED ARACHIDONATE INCORPORATION FROMPLASMA INTO BRAIN MICROVESSELS OF AWAKE RAT

The cholinergic agonist, arecoline, was used to examine the effects of cholinergic stimulation upon incorporation of radiolabeled arachidoni c acid from blood into cerebral microvessels of awake rats. Animals re ceived a single I.P. injection of arecoline (1 mg/kg) followed 3 to 5 minutes later by a 5 minute intravenous infusion of [1-C-14]arachidoni c acid (API) (170 mu Ci/kg) via the femoral vein; Timed arterial blood samples were collected over 20 minutes following the start of infusio n, after which the animal was killed, and the brain was removed. The i ncorporation coefficient k for [1-C-14]AA was approximately 2-fold hi gher in microvessels isolated from arecoline-injected than from sham-i njected animals. The data demonstrate in an in vivo paradigm, that act ivation of cholinergic pathways within the rat CNS stimulates arachido nic acid turnover in cerebral microvessels. This suggests a direct inv olvement of this fatty acid in second messenger function within microv essel endothelial cells and possibly attached pericytes.