Characterization of action potential-triggered [Ca2+](1) transients in single smooth muscle cells of guinea-pig ileum

被引:20
作者
Kohda, M [1 ]
Komori, S [1 ]
Unno, T [1 ]
Ohashi, H [1 ]
机构
[1] GIFU UNIV, FAC AGR, DEPT VET SCI, PHARMACOL LAB, GIFU 50111, JAPAN
关键词
action potential; Ca2+](1); excitation-contraction coupling; Ca2+-induced Ca2+ release; smooth muscle; guinea-pig ileum;
D O I
10.1038/sj.bjp.0701407
中图分类号
R9 [药学];
学科分类号
1007 ;
摘要
1 To characterize increases in cytosolic free Ca2+ concentration ([Ca2+](i)) associated with discharge of action potentials, membrane potential and [Ca2+](i) were simultaneously recorded from single smooth muscle cells of guinea-pig ileum by use of a combination of nystatin-perforated patch clamp and fura-2 fluorimetry techniques. 2 A single action potential in response to a depolarizing current pulse elicited a transient rise in [Ca2+](i). When the duration of the current pulse was prolonged, action potentials were repeatedly discharged during the early period of the pulse duration with a progressive decrease in overshoot potential, upstroke rate and repolarization rate. However, such action potentials could each trigger [Ca2+](i) transients with an almost constant amplitude. 3 Nicardipine (1 mu M) and La3+ (10 mu M), blockers of voltage-dependent Ca2+ channels (VDCCs), abolished both the action potential discharge and the [Ca2+](i) transient. 4 Charybdotoxin (ChTX, 300 nM) and tetraethylammonium (TEA, 2 mM), blockers of large conductance Ca2+-activated K+ channels, decreased the rate of repolarization of action potentials but increased the amplitude of [Ca2+](i) transients. 5 Thapsigargin (1 mu M), an inhibitor of SR Ca2+-ATPase, slowed the falling phase and somewhat increased the amplitude, of action potential-triggered [Ca2+](i) transients without affecting action potentials. In addition, in voltage-clamped cells, the drug had little effect on the voltage step-evoked Ca2+ current but exerted a similar effect on its concomitant rise in [Ca2+](i) to that on the action potential-triggered [Ca2+](i) transient. 6 Similar action potential-triggered [Ca2+](i) transients were induced by brief exposures to high-K+ solution. They were not decreased, but rather increased, after depletion of intracellular Ca2+ stores by a combination of ryanodine (30 mu M) and caffeine (10 mM) through an open-lock of Ca2+-induced Ca2+ release (CICR)-related channels. 7 The results show that action potentials, discharged repeatedly during the early period of a long membrane depolarization, undergo a progressive change in configuration but can each trigger a constant rise in [Ca2+](i). Intracellular Ca2+ stores have a role, especially in accelerating the falling phase of the action potential-triggered [Ca2+](i) transients by replenishing cytosolic Ca2+. No evidence was provided for the involvement of CICR in the action potential-triggered [Ca2+](i) transient.
引用
收藏
页码:477 / 486
页数:10
相关论文
共 35 条
[1]  
AXELSSON J, 1970, SMOOTH MUSCLE, P289
[2]   SPONTANEOUS TRANSIENT OUTWARD CURRENTS IN SINGLE VISCERAL AND VASCULAR SMOOTH-MUSCLE CELLS OF THE RABBIT [J].
BENHAM, CD ;
BOLTON, TB .
JOURNAL OF PHYSIOLOGY-LONDON, 1986, 381 :385-406
[3]   MECHANISMS OF ACTION OF TRANSMITTERS AND OTHER SUBSTANCES ON SMOOTH-MUSCLE [J].
BOLTON, TB .
PHYSIOLOGICAL REVIEWS, 1979, 59 (03) :606-718
[4]  
BOLTON TB, 1993, POTASSIUM CHANNEL MO, P144
[5]  
CHEN Q, 1992, ADV 2 MESSENGER PHOS, P335
[6]   Voltage-dependent calcium currents and cytosolic calcium in equine airway myocytes [J].
Fleischmann, BK ;
Wang, YX ;
Pring, M ;
Kotlikoff, MI .
JOURNAL OF PHYSIOLOGY-LONDON, 1996, 492 (02) :347-358
[7]   CONTRIBUTION OF CA2+-INDUCED CA2+ RELEASE TO THE [CA2+]I TRANSIENTS IN MYOCYTES FROM GUINEA-PIG URINARY-BLADDER [J].
GANITKEVICH, VY ;
ISENBERG, G .
JOURNAL OF PHYSIOLOGY-LONDON, 1992, 458 :119-137
[8]   DEPOLARIZATION-MEDIATED INTRACELLULAR CALCIUM TRANSIENTS IN ISOLATED SMOOTH-MUSCLE CELLS OF GUINEA-PIG URINARY-BLADDER [J].
GANITKEVICH, VY ;
ISENBERG, G .
JOURNAL OF PHYSIOLOGY-LONDON, 1991, 435 :187-205
[9]   EFFICACY OF PEAK CA2+ CURRENTS (I-CA) AS TRIGGER OF SARCOPLASMIC-RETICULUM CA2+ RELEASE IN MYOCYTES FROM THE GUINEA-PIG CORONARY-ARTERY [J].
GANITKEVICH, VY ;
ISENBERG, G .
JOURNAL OF PHYSIOLOGY-LONDON, 1995, 484 (02) :287-306
[10]   CA2+ AND SR2+ ENTRY INDUCED CA2+ RELEASE FROM THE INTRACELLULAR CA2+ STORE IN SMOOTH-MUSCLE CELLS OF RAT PORTAL-VEIN [J].
GREGOIRE, G ;
LOIRAND, G ;
PACAUD, P .
JOURNAL OF PHYSIOLOGY-LONDON, 1993, 472 :483-500