Cardiovascular regulation by brain acetylcholine.

Evidence is presented that implicates brain acetylcholine (ACh) in the control of blood pressure (BP) and in hypertension. Central cholinergic stimulation by muscarinic agonists or inhibitors of acetylcholinesterase (AChE) evokes a hypertensive response in several animal species, including humans. The elevation in BP after injection of AChE inhibitors is mediated centrally by ACh acting on muscarinic receptors and peripherally through increased sympathetic nerve activity. The pressor response is accompanied by inhibition of reflex tachycardia and potentiation of both reflex bradycardia and the pressor reflex to carotid artery occlusion. Intracerebroventricular injection of hemicholinium 3 in doses that deplete brain ACh lowers BP in the spontaneously hypertensive and the deoxycorticosterone acetate-salt hypertensive rat. Little or no reduction occurs in the normotensive rat or in animals made hypertensive by aortic coarctation. In addition, atropine and the selective central muscarinic receptor antagonist N-(4-diethylamino-2-butynyl)-succinimide lower BP in the spontaneously hypertensive rat but not in the normotensive rat.