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Effects of BRL 38227 on potassium currents in smooth muscle cells isolated from rabbit portal vein and human mesenteric artery
Author(s) -
Russell Scott N.,
Smirnov Sergey V.,
Aaronson Philip I.
Publication year - 1992
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/j.1476-5381.1992.tb09017.x
Subject(s) - cromakalim , tetraethylammonium , glibenclamide , chemistry , phentolamine , potassium channel , endocrinology , medicine , voltage clamp , patch clamp , pharmacology , electrophysiology , potassium , biochemistry , receptor , organic chemistry , diabetes mellitus
1 Single smooth muscle cells were isolated from the rabbit portal vein and the human mesenteric artery and whole cell currents recorded at room temperature from either cell type by the whole cell voltage clamp technique. 2 In the rabbit portal vein cells addition of 10 μ m BRL 38227 induced a quasi‐instantaneous, voltage‐insensitive and time‐independent current which had a reversal potential of −75 mV under experimental conditions where the calculated E K was −83 mV. 3 Cells were held at 0 mV and BRL 38227 was added cumulatively to construct a dose‐response relationship. BRL 38227 (0.03–10 μ m ) caused a dose‐dependent outward shift in the holding current with an EC 50 of 1.3 μ m . 4 BRL 38227 (10 μ m ) had no effect on the delayed rectifier K + current measured in the presence of 5 m m tetraethylammonium and no effect on the Ca 2+ ‐activated K + current measured in the presence of 5 m m 4‐aminopyridine. Similarly BRL 38227 had no effect on the Ca 2+ current. 5 The BRL 38227‐induced current was blocked by glibenclamide (10 μ m ) and phentolamine (100 μ m ), specific blockers of the ATP‐sensitive K + current in single cells. 6 In human isolated mesenteric artery cells, BRL 38227 (10 μ m ) induced a glibenclamide‐sensitive current similar to, but smaller than, that observed in the rabbit portal vein. 7 We conclude that in these cells, BRL 38227 activates a potassium conductance which has the electrophysiological and pharmacological characteristics of ATP‐sensitive K + channels.