Interaction of spinal cholinergic, glutamatergic, and nitric oxide systems in central cardiovascular regulation

Abstract

Recent studies in this laboratory have demonstrated the ability of acetylcholine receptor agonists to- pr?duce sys~emic arterial pressor resp~nses through stimulation of spinal muscarinic receptors; · In urethane-anesthetized rats a ·new -surgical procedure was employed to permit microinjection of drugs . .into the cerebrospinal fluid surrounding the medulla without significant redistribution to spinal sites and vice versa. Pretreatment with intracisternal (medullary level) injection of 10 ug of atropine significantly · inhibited the expression of the pressor response :produced by intr~thecal injection of 5 ug of carbachol. This inhibition was due at least partly to the interruption of a medullary component of a spinobulbar pathway involving :'-medullary muscarinic receptors. It was not due to redistribution of atropine from medullary to spinal sites since significant levels of atropine were not detected in the spinal cord after intracisternal iJ?.jection of the drug. The remainder of the pressor .response to ~trathecal carbachol after medullary muscarinic receptor blockade was most likely due to interactions within the spinal cord itself.