Medical Pharmacology Chapter 6: Autonomic Pharmacology: Cholinergic Drugs
Signal Transduction: Comparison of Muscarinic and Nicotinc Receptors
Nicotinic Receptors characteristics:
The receptor is a ligand-gated ion channels.
Agonist effects at the receptor are blocked by tubocurarine.
Receptor activation results in:
A rapid increases of Na+ and Ca2+ conductance (increased movement of these ions across the membrane).
Deplorization of the membrane (membrane potential becomes less negative).
Subtypes based on differing subunit composition: Muscle and Neuronal Classification
Muscarinic Receptors characteristics:
This receptor is a G-protein coupled receptor system.
Compared to nicotinic receptors, muscarinic receptors exhibit slower responses.
Agonist effects blocked by atropine
At least five receptor subtypes have been described by molecular cloning.
Variants have distinct anatomical locations and differing molecular specificities
Lefkowitz, R.J, Hoffman, B.B and Taylor, P. Neurotransmission: The Autonomic and Somatic Motor Nervous Systems, In, Goodman and Gillman's The Pharmacological Basis of Therapeutics, (Hardman, J.G, Limbird, L.E, Molinoff, P.B., Ruddon, R.W, and Gilman, A.G.,eds) The McGraw-Hill Companies, Inc.,1996, pp.112-137.