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Functions of large conductance Ca 2+ ‐activated (BK Ca ), delayed rectifier (K V ) and background K + channels in the control of membrane potential in rabbit renal arcuate artery
Author(s) -
Prior H. M.,
Yates M. S.,
Beech D. J.
Publication year - 1998
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1111/j.1469-7793.1998.159bi.x
Subject(s) - chemistry , membrane potential , conductance , bk channel , analytical chemistry (journal) , physics , chromatography , biochemistry , condensed matter physics
1 The types of K + channel which determine the membrane potential of arcuate artery smooth muscle cells were investigated by patch‐clamp recording from isolated cells and lumenal diameter measurements from intact pressurized renal arcuate arteries. 2 Single cells had a mean resting potential of ‐38 mV and were depolarized by 130 mM K + but not by the Cl − channel blocker 4,4′‐diisothiocyanatostilbene‐2,2′‐disulphonic acid (DIDS). 3 Iberiotoxin did not affect the resting potential but inhibited spontaneous transient hyperpolarizations. Iberiotoxin or 1 mM tetraethylammonium (TEA + ) constricted intact arteries. 3,4‐Diaminopyridine (3,4‐DAP)‐sensitive delayed rectifier K + (K V ) channel current was elicited by depolarization but 3,4‐DAP did not affect the resting potential or induce constriction in the intact artery. 4 A voltage‐independent K + current was inhibited by ≥ 0·1 mM barium (Ba 2+ ) and unaffected by iberiotoxin, glibenclamide, apamin, 3,4‐DAP and ouabain. In six out of ten cells, 1 mM Ba 2+ depolarized the resting potential, while in the other cells the potential was resistant to all of the K + channel blockers and ouabain. Ba 2+ (0·1‐1 mM) constricted the intact artery, but 10 μM Ba 2+ , 1 μM glibenclamide or 100 nM apamin had no effect. 5 The data suggest that resting potential is determined by background K + channels, one type being Ba 2+ sensitive and voltage independent, and another type being poorly defined due to its resistance to any inhibitor. Large conductance Ca 2+ ‐activated K + (BK Ca ) and K V channels do not determine the resting potential but have separate functions to underlie transient Ca 2+ ‐induced hyperpolarizations and to protect against depolarization past about ‐30 mV.