Characterization of a P-type calcium current in a crayfish motoneuron and its selective modulation by impulse activity

被引:24
作者
Hong, SJ [1 ]
Lnenicka, GA [1 ]
机构
[1] SUNY ALBANY, DEPT BIOL SCI, NEUROBIOL RES CTR, ALBANY, NY 12222 USA
关键词
D O I
10.1152/jn.1997.77.1.76
中图分类号
Q189 [神经科学];
学科分类号
071006 ;
摘要
Previous studies have demonstrated that the voltage-dependent Ca2+ current recorded from the cell body of the crayfish abdominal motoneuron, F3, undergoes a long-term reduction as a result of increased impulse activity. The properties of the Ca2+ channels undergoing this long-term change were examined with the use of two-electrode voltage-clamp techniques. The Ca2+ current was activated at -50 to -40 mV and its amplitude was maximal at 0 mV (-135.0 +/- 25.8 nA, mean +/- SE, n = 14). The current-voltage relationship and the greater sensitivity of the Ca2+ channel to Cd2+ than Ni2+ indicated that Ca2+ influx occurs through high-voltage-activated (HVA) Ca2+ channels. Loose-patch recordings demonstrated that the Ca2+ current was generated by the membrane of the cell body. When Ba2+ was substituted for extracellular Ca2+ there was a 40% increase in the amplitude of the inward current and a negative shift of similar to 10 mV in the I-V relationship. Application of the P-type Ca2+ channel antagonist omega-agatoxin TVA (omega-AgTX IVA) produced a significant 33% (n = 6) reduction in the peak amplitude of the Ba2+ current, whereas neither the L-type Ca2+ channel antagonist nifedipine nor the N-type channel antagonist omega-conotoxin GVIA produced a reduction in the Ba2+ current. The voltage-dependent activation of this P-type (omega-AgTX-TVA-sensitive) Ca2+ channel was similar to previously identified P-type channels, but different from that of the non-P-type (omega-AgTX-IVA-resistant) Ca2+ channels. When Ca2+ currents were measured 6-7 h after an increase in impulse activity (5-Hz stimulation for 45-60 min), there was a 43% reduction in the amplitude of the P-type current, but no significant changes in the non-P-type current amplitude. These results demonstrate that at least two subtypes of HVA Ca2+ channels contribute to the macroscopic Ca2+ current observed in the cell body of this crayfish phasic motoneuron: one belongs to the previously described P-type Ca2+ channel and the other(s) does not belong to the N-, L-, or P-type Ca2+ channel. The long-term, Ca2+-dependent reduction in Ca2+ current previously demonstrated in motoneuron F3 is produced by the selective reduction of this P-type Ca2+ current. This activity-dependent reduction in the P-type Ca2+ current is likely involved in the long-term depression of transmitter release observed at the neuromuscular synapses of this motoneuron.
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页码:76 / 85
页数:10
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共 63 条
  • [41] THE CALPAINS
    MELLONI, E
    PONTREMOLI, S
    [J]. TRENDS IN NEUROSCIENCES, 1989, 12 (11) : 438 - 444
  • [42] MERCIER AJ, 1989, J EXP BIOL, V145, P9
  • [43] MULTIPLE CALCIUM CHANNELS AND NEURONAL FUNCTION
    MILLER, RJ
    [J]. SCIENCE, 1987, 235 (4784) : 46 - 52
  • [44] P-TYPE CALCIUM CHANNELS IN RAT CENTRAL AND PERIPHERAL NEURONS
    MINTZ, IM
    ADAMS, ME
    BEAN, BP
    [J]. NEURON, 1992, 9 (01) : 85 - 95
  • [45] P-TYPE CALCIUM CHANNELS BLOCKED BY THE SPIDER TOXIN OMEGA-AGA-IVA
    MINTZ, IM
    VENEMA, VJ
    SWIDEREK, KM
    LEE, TD
    BEAN, BP
    ADAMS, ME
    [J]. NATURE, 1992, 355 (6363) : 827 - 829
  • [46] NERBONNE JM, 1987, J NEUROSCI, V7, P882
  • [47] 3 TYPES OF NEURONAL CALCIUM-CHANNEL WITH DIFFERENT CALCIUM AGONIST SENSITIVITY
    NOWYCKY, MC
    FOX, AP
    TSIEN, RW
    [J]. NATURE, 1985, 316 (6027) : 440 - 443
  • [48] PEPTIDE NEUROTOXINS FROM FISH-HUNTING CONE SNAILS
    OLIVERA, BM
    GRAY, WR
    ZEIKUS, R
    MCINTOSH, JM
    VARGA, J
    RIVIER, J
    DESANTOS, V
    CRUZ, LJ
    [J]. SCIENCE, 1985, 230 (4732) : 1338 - 1343
  • [49] PENINGTON NJ, 1995, J NEUROSCI, V15, P5719
  • [50] EFFECT OF OMEGA-CONOTOXIN GVIA ON NEUROTRANSMITTER RELEASE AT THE MOUSE NEUROMUSCULAR-JUNCTION
    PROTTI, DA
    SZCZUPAK, L
    SCORNIK, FS
    UCHITEL, OD
    [J]. BRAIN RESEARCH, 1991, 557 (1-2) : 336 - 339