Biochemical determinations of cholinergic innervation in cerebral arteries

Endogenous choline acetyltransferase (ChAT) activity and high affinity (HA) 3H-choline uptake can be assayed specifically and used to quantify cholinergic neuronal mechanisms. In general, arteries at the base of the brain in the cat and rabbit were distinguished by high and in the dog by lower ChAT activity and 3H-choline levels of uptake. There was a linear relationship between the mean values of the observations from of the two assays on given cerebral arteries from the three species (r = 0.871,P less than 0.001). Since ChAT activity and HA 3H-choline uptake essentially are confined to cholinergic nerve terminals, our results imply that the Circle of Willis and its main branches in the cat, rabbit, and dog are cholinergically innervated.