Muscarinic Receptor Subtypes

Abstract

CHOLINERGIC neurons affect tissues by releasing the neurotransmitter acetylcholine, which stimulates acetylcholine receptors on the cell surface. These receptors are classified as nicotinic or muscarinic receptors on the basis of their response to the alkaloids nicotine and muscarine.¹ The nicotinic receptors are widely distributed in tissues and mediate the actions of acetylcholine in the neurons of striated muscles, autonomic ganglia, and the central nervous system.² Muscarinic receptors are key participants in many physiologic processes, such as nerve-to-nerve transmission, smooth-muscle contraction, and exocrine and endocrine secretion. Clinically, they have a major role in many pathologic processes. Muscarinic agonists and antagonists, popularly . . .