Butanedione monoxime promotes voltage-dependent inactivation of L-type calcium channels in heart. Effects on gating currents

被引:40
作者
Ferreira, G [1 ]
Artigas, P [1 ]
Pizarro, G [1 ]
Brum, G [1 ]
机构
[1] FAC MED, DEPT BIOFIS, MONTEVIDEO 11800, URUGUAY
关键词
2,3-butanedione monoxime; calcium channels; charge movement; guinea-pig;
D O I
10.1006/jmcc.1996.0321
中图分类号
R5 [内科学];
学科分类号
1002 ; 100201 ;
摘要
The effect of 20 mM extracellularly applied 2,3-Butanedione monoxime (BDM) on L-type Ca2+ channel charge movement current was studied in whole-cell voltage-clamped guinea-pig ventricular myocytes. Intramembraneous charge movement in response to depolarizing pulses (charge 1), was reduced after the application of BDM. The effect was more pronounced at the OFF of the charge transient (41%) than at the ON (7%). The steady-state availability curve of charge 1 was shifted to the left; the magnitude of the voltage shift was similar to the shift in Ca2+ current availability. Charge movement recorded in the negative voltage range (charge 2) after conditioning depolarizing pulses of different duration, was increased by BDM. For a 300-ms conditioning pulse, charge 2 measured during a negative test pulse increased 40% (in Ba2+ external solution) or 35% (In Ca2+ external solution). These results show that BDM promotes voltage-dependent inactivation of L-type Ca2+ channels in parallel with charge interconversion between intramembranous charges 1 and 2. Mechanistically they are consistent either with dephosphorylation or a dihydropyridine-like action, but argue against open channel block as the mechanism of the effect of the drug. (C) 1997 Academic Press Limited.
引用
收藏
页码:777 / 787
页数:11
相关论文
共 36 条
[1]   THE EFFECT OF A CHEMICAL PHOSPHATASE ON SINGLE CALCIUM CHANNELS AND THE INACTIVATION OF WHOLE-CELL CALCIUM CURRENT FROM ISOLATED GUINEA-PIG VENTRICULAR MYOCYTES [J].
ALLEN, TJA ;
CHAPMAN, RA .
PFLUGERS ARCHIV-EUROPEAN JOURNAL OF PHYSIOLOGY, 1995, 430 (01) :68-80
[2]  
ALLEN TJA, 1995, J PHYSL, V487, pP137
[3]   NONLINEAR CHARGE MOVEMENT IN MAMMALIAN CARDIAC VENTRICULAR CELLS - COMPONENTS FROM NA AND CA CHANNEL GATING [J].
BEAN, BP ;
RIOS, E .
JOURNAL OF GENERAL PHYSIOLOGY, 1989, 94 (01) :65-93
[4]   OXIMES - ENZYMATIC SLOW CHANNEL ANTAGONISTS IN CANINE CARDIAC PURKINJE-FIBERS [J].
BERGEY, JL ;
REISER, J ;
WIGGINS, JR ;
FREEMAN, AR .
EUROPEAN JOURNAL OF PHARMACOLOGY, 1981, 71 (2-3) :307-319
[5]   INTRAMEMBRANE CHARGE MOVEMENT IN FROG SKELETAL-MUSCLE FIBERS - PROPERTIES OF CHARGE-2 [J].
BRUM, G ;
RIOS, E .
JOURNAL OF PHYSIOLOGY-LONDON, 1987, 387 :489-517
[6]   VOLTAGE SENSORS OF THE FROG SKELETAL-MUSCLE MEMBRANE REQUIRE CALCIUM TO FUNCTION IN EXCITATION CONTRACTION COUPLING [J].
BRUM, G ;
FITTS, R ;
PIZARRO, G ;
RIOS, E .
JOURNAL OF PHYSIOLOGY-LONDON, 1988, 398 :475-505
[7]   THE EFFECT OF OXIMES ON THE DIHYDROPYRIDINE-SENSITIVE CA CURRENT OF ISOLATED GUINEA-PIG VENTRICULAR MYOCYTES [J].
CHAPMAN, RA .
PFLUGERS ARCHIV-EUROPEAN JOURNAL OF PHYSIOLOGY, 1993, 422 (04) :325-331
[8]  
CHAPMAN RA, 1995, J PHYSIOL-LONDON, V483P, pP19
[9]   EFFECT OF 2,3-BUTANEDIONE 2-MONOXIME ON SLOW INWARD AND TRANSIENT OUTWARD CURRENTS IN RAT VENTRICULAR MYOCYTES [J].
COULOMBE, A ;
LEFEVRE, IA ;
DEROUBAIX, E ;
THURINGER, D ;
CORABOEUF, E .
JOURNAL OF MOLECULAR AND CELLULAR CARDIOLOGY, 1990, 22 (08) :921-932
[10]  
DEARMAS R, 1993, BIOPHYS J, V64, pA240