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Schematic diagram of two types of ion channels regulated by receptors and drugs. A. Diagram of a voltage-activated Na+ channel with the pore in the open
and closed state. The P loops are shown in blue, angled into the pore to form the selectivity filter. The S4 helices forming the voltage sensor are shown in
orange, with the positively charged amino acids displayed as red dots. B. Ligand-gated nicotinic acetylcholine receptor expressed in the skeletal muscle
neuromuscular junction. The pore is made up of five subunits, each with a large extracellular domain and four transmembrane helices (one of these
subunits is shown at the left of panel B). The helix that lines the pore is shown in blue. The receptor is composed of 2 α subunits, and β, γ, and δ subunits.
See text for discussion of other ligand-gated ion channels. Detailed descriptions of specific channels are given throughout the text in relation to the
Source: Pharmacodynamics: Molecular Mechanisms of Drug Action, Goodman & Gilman's: The Pharmacological Basis of Therapeutics, 12e
therapeutic actions of drugs affecting these channels (see especially Chapters 11, 14 and 20). (Adapted with permission from Purves, D, Augustine, GJ,
Brunton
LL, Chabner
BA, Knollmann
Goodman
& Gilman's:
The Pharmacological
Basis of Therapeutics,
Fitzpatrick, D,Citation:
Hall, WC,
LaMantia,
AS, McNamara,
JO, andBC.
White,
LE (eds).
Neuroscience,
4ed. Sinauer Associates,
Inc., 2008.) 12e; 2011 Available at:
http://mhmedical.com/ Accessed: April 29, 2017
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