SUSTAINED OUTWARD CURRENT OBSERVED AFTER ITO1 INACTIVATION IN RABBIT ATRIAL MYOCYTES IS A NOVEL CL- CURRENT

被引:45
作者
DUAN, DY
FERMINI, B
NATTEL, S
机构
[1] MONTREAL HEART INST, 5000 BELANGER ST E, MONTREAL H1T 1C8, QUEBEC, CANADA
[2] UNIV MONTREAL, DEPT MED, MONTREAL H3C 3G7, PQ, CANADA
[3] MCGILL UNIV, DEPT PHARMACOL & THERAPEUT, MONTREAL H3G 1Y6, QUEBEC, CANADA
来源
AMERICAN JOURNAL OF PHYSIOLOGY | 1992年 / 263卷 / 06期
关键词
CHLORIDE CURRENT; ACTION POTENTIAL; CARDIAC OUTWARD CURRENTS; TRANSIENT OUTWARD CURRENT; CARDIAC REPOLARIZATION; ATRIAL ARRHYTHMIAS; ANTIARRHYTHMIC DRUGS;
D O I
10.1152/ajpheart.1992.263.6.H1967
中图分类号
Q4 [生理学];
学科分类号
071003 ;
摘要
In rabbit atrial myocytes, depolarization of the membrane results in a rapidly activating transient outward current (I(to)) that then decays to a sustained level. The sustained current (I(sus)) remains constant for at least 5 s during continued depolarization. The present study was designed to identify the ionic mechanism underlying I(sus) with the use of whole cell voltage-clamp techniques. After exposure to 2 mM 4-aminopyridine (4-AP), the 4-AP-sensitive transient outward current (I(to1)) was abolished, but I(sus) was unaffected. I(sus) was not blocked by the K+ channel blockers tetraethylammonium chloride and Ba2+, was not changed by increasing superfusate K+ concentration, and was still present when K+ was replaced by Cs+ in both the superfusate and the pipette. I(sus) was significantly reduced by the Cl- transport blockers 4-acetamido-4'-isothiocyanatostilbene-2.2'-disulfonic acid and 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid. The current-voltage relations of I(sus) showed outward rectification, and the reversal potential of I(sus) shifted with changes in the transmembrane Cl- gradient in the fashion expected for a Cl- current. We conclude that I(sus) in rabbit atrium is due to a noninactivating Cl- current which, unlike previously described cardiac Cl- currents, is manifest in the absence of exogenous stimulators of adenosine 3',5'-cyclic monophosphate formation, cytosolic Ca2+ transients, or cell swelling.
引用
收藏
页码:H1967 / H1971
页数:5
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