ROLE OF VOLTAGE-DEPENDENT IONIC CURRENTS IN COUPLING GLUCOSE STIMULATION TO INSULIN-SECRETION IN CANINE PANCREATIC-ISLET B-CELLS

被引:41
作者
PRESSEL, DM
MISLER, S
机构
[1] WASHINGTON UNIV,MED CTR,DEPT CELL BIOL PHYSIOL,ST LOUIS,MO 63110
[2] WASHINGTON UNIV,MED CTR,PROGRAM NEUROSCI,ST LOUIS,MO 63110
关键词
PANCREATIC ISLET B-CELLS; ISLET CELL ELECTROPHYSIOLOGY; STIMULUS-SECRETION COUPLING; NA+ CURRENT; CA2+ CURRENT; K+ CURRENT;
D O I
10.1007/BF01994357
中图分类号
Q5 [生物化学]; Q7 [分子生物学];
学科分类号
071010 ; 081704 ;
摘要
Glucose-induced electrical activity in canine pancreatic islet B cells is distinct from that in rodent islets, though both display Ca2+-dependent insulin secretion. Rodent islet B cells undergo regular bursts of Ca2+-dependent action potentials, while canine islet B cells generate isolated Na+-dependent action potentials which often give way to a plateau depolarization. Here we present evidence to reconcile the species difference in electrical activity with the similarity of Ca2+ dependence of secretion. (i) In canine B cells increasing glucose concentrations produce membrane depolarization and increasing frequency of Na(o)-dependent action potentials until a background membrane potential (approximately -40 mV) is reached where Na+ currents are inactivated. (ii) Voltage-dependent Ca2+ currents are present which are activated over the voltage excursion of the action potential (-50 to +20 mV) and inactivate slowly, (over seconds) in the range of the plateau depolarization (-40 to -25 mV). Hence, they are available to contribute to both phases of depolarization. (iii) Tetrodotoxin (TTX) reduces by half an early transient phase of glucose-stimulated insulin secretion but not a subsequent prolonged plateau phase. The transient phase of secretion often corresponds well in time to the period of initial high frequency action potential activity. These latter results suggest that in canine B cells voltage-dependent Na+ and Ca2+ currents mediate biphasic glucose-induced insulin secretion. The early train of Na+-dependent action potentials, by transiently activating Ca2+ channels and allowing pulsatile Ca2+ entry, may promote an early transient phase of insulin secretion. The subsequent sustained plateau depolarization, by allowing sustained Ca2+ entry, may permit steady insulin release.
引用
收藏
页码:239 / 253
页数:15
相关论文
共 37 条
  • [21] CHARACTERIZATION OF THE PROCESS OF SODIUM-CALCIUM EXCHANGE IN PANCREATIC-ISLET CELLS
    PLASMAN, PO
    LEBRUN, P
    HERCHUELZ, A
    [J]. AMERICAN JOURNAL OF PHYSIOLOGY, 1990, 259 (06): : E844 - E850
  • [22] PRESSEL D, 1989, Biophysical Journal, V55, p540A
  • [23] PRESSEL D M, 1991, Biophysical Journal, V59, p87A
  • [24] SODIUM-CHANNELS CONTRIBUTE TO ACTION-POTENTIAL GENERATION IN CANINE AND HUMAN PANCREATIC-ISLET B-CELLS
    PRESSEL, DM
    MISLER, S
    [J]. JOURNAL OF MEMBRANE BIOLOGY, 1990, 116 (03) : 273 - 280
  • [25] AUTOMATED-METHOD FOR ISOLATION OF HUMAN PANCREATIC-ISLETS
    RICORDI, C
    LACY, PE
    FINKE, EH
    OLACK, BJ
    SCHARP, DW
    [J]. DIABETES, 1988, 37 (04) : 413 - 420
  • [26] VOLTAGE-ACTIVATED CURRENTS IN GUINEA-PIG PANCREATIC-ALPHA-2 CELLS - EVIDENCE FOR CA-2+-DEPENDENT ACTION-POTENTIALS
    RORSMAN, P
    HELLMAN, B
    [J]. JOURNAL OF GENERAL PHYSIOLOGY, 1988, 91 (02) : 223 - 242
  • [27] SINGLE CA CHANNEL CURRENTS IN MOUSE PANCREATIC B-CELLS
    RORSMAN, P
    ASHCROFT, FM
    TRUBE, G
    [J]. PFLUGERS ARCHIV-EUROPEAN JOURNAL OF PHYSIOLOGY, 1988, 412 (06): : 597 - 603
  • [28] CALCIUM AND DELAYED POTASSIUM CURRENTS IN MOUSE PANCREATIC BETA-CELLS UNDER VOLTAGE-CLAMP CONDITIONS
    RORSMAN, P
    TRUBE, G
    [J]. JOURNAL OF PHYSIOLOGY-LONDON, 1986, 374 : 531 - 550
  • [29] ANALYSIS AND USE OF THE PERFORATED PATCH TECHNIQUE FOR RECORDING IONIC CURRENTS IN PANCREATIC BETA-CELLS
    SALA, S
    PARSEY, RV
    COHEN, AS
    MATTESON, DR
    [J]. JOURNAL OF MEMBRANE BIOLOGY, 1991, 122 (02) : 177 - 187
  • [30] EXPRESSION OF A RAPID, LOW-VOLTAGE THRESHOLD K-CURRENT IN INSULIN-SECRETING CELLS IS DEPENDENT ON INTRACELLULAR CALCIUM BUFFERING
    SATIN, LS
    HOPKINS, WF
    FATHERAZI, S
    COOK, DL
    [J]. JOURNAL OF MEMBRANE BIOLOGY, 1989, 112 (03) : 213 - 222