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Permeability and single‐channel properties of mesenteric, basilar, and septal (coronary) artery smooth‐muscle P2X receptors
Author(s) -
Lewis Carolyn J.,
Davies Noel W.,
Evans Richard J.
Publication year - 2001
Publication title -
drug development research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.582
H-Index - 60
eISSN - 1098-2299
pISSN - 0272-4391
DOI - 10.1002/ddr.1111
Subject(s) - homomeric , receptor , biophysics , basilar artery , chemistry , mesenteric arteries , medicine , endocrinology , artery , anatomy , biology , biochemistry , protein subunit , gene
P2X 1 receptors for ATP are expressed in vascular smooth muscle and are thought to underlie the native artery smooth muscle rapidly desensitising α,β‐methylene ATP (α,β‐meATP) sensitive P2X receptor phenotype. We have characterised the ionic permeability and single‐channel conductance from rat mesenteric, basilar, and septal (coronary) arteries. The relative permeabilities (P X /P Na ) to methylamine, dimethylamine, and Tris were essentially the same for all three arteries and give an estimate of the minimum diameter of the ionic pore as 0.8 nm. The P2X receptor channels in arteries had a high calcium permeability (P Ca 2+ /P Na ∼3.5). In outside‐out patches, α,β‐meATP evoked transient currents with a single‐channel conductance of ∼12 pS (in physiological solution with 2.5 mM Ca 2+ and 1 mM Mg 2+ ). The single‐channel conductance was increased to ∼17 pS with a 0.1 mM Ca 2+ ‐ and nominally Mg 2+ ‐free physiological solution. These properties for artery P2X receptors are essentially the same as for recombinant P2X 1 receptors and confirm that homomeric P2X 1 receptors underlie the native P2X receptor current phenotype in these arteries. Drug Dev. Res. 52:164–169, 2001. © 2001 Wiley‐Liss, Inc.