Sodium-dependent plateau potentials in cultured retzius cells of the medicinal leech

被引:16
作者
Angstadt, JD
Choo, JJ
机构
[1] Department of Biology, Siena College, Loudonville
关键词
D O I
10.1152/jn.1996.76.3.1491
中图分类号
Q189 [神经科学];
学科分类号
071006 ;
摘要
1. Individual leech Retzius (Rz) cells were removed from midbody ganglia and plated in cell culture on concanavalin A or polylysine. Experiments on the majority of cells were performed after 6-11 days in culture. Isolated Rz cells were superfused with normal leech saline (NS), cobalt saline (Ca2+ replaced with Co2+), or one of a variety of other modified salines. 2. Prolonged plateau potentials (PPs) with durations ranging from several seconds to nearly 2 min were evoked in isolated Rz cells in response to 1-s depolarizing current pulses delivered under discontinuous current clamp. Some PPs terminated spontaneously while others were terminated with hyperpolarizing current pulses. PPs were associated with a dramatic increase in the input conductance of the neuron. The PP decayed slightly over time, and this decay was accompanied by a small decrease in the input conductance. 3. PP duration was enhanced by penetrating cells with electrodes containing tetraethylammonium (TEA) and by bathing cells in Co2+ saline, but PPs were evoked also in NS and using electrodes without TEA. The effects of TEA and Co2+ saline suggest that voltage-dependent and especially calcium-dependent outward currents normally suppress plateau formation. 4. PPs occurred most reliably in neurons with extensive neurite sprouting. Isolated somata with few or no neurites usually failed to express PP, although there were several exceptions to this trend. 5. PPs persisted when Ca2+ was replaced with either of the calcium channel blockers Co2+, Ni2+, or Mn2+, when 200 mu M Cd2+ was added to normal saline, or when Na+ was replaced with Li+. In contrast, PPs were eliminated rapidly when Na+ was replaced with N-methyl-D-glucamine. 6. Isolated Rz cells also expressed repetitive PPs either spontaneously or in response to injection of sustained depolarizing current. Spontaneous repetitive PPs were suppressed by hyperpolarizing current. Repetitive PPs in isolated Rz cells are similar in many respects to the bursting electrical activity induced by Co2+ Saline in Rz and other neurons in intact ganglia. 7. The ionic dependence and prolonged duration of PPs suggest that these responses are generated by a persistent voltage-dependent Na+ current. A quantitative computer simulation of PPs was achieved using a depolarization-activated Na+ conductance with very slow inactivation. Repetitive PPs were simulated by addition of a slow outward current in the form of an electrogenic pump.
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页码:1491 / 1502
页数:12
相关论文
共 30 条
[1]  
ALZHEIMER C, 1993, J NEUROSCI, V13, P660
[2]  
ANGSTADT JD, 1991, J NEUROSCI, V11, P746
[3]   SYNCHRONIZED OSCILLATORY ACTIVITY IN LEECH NEURONS INDUCED BY CALCIUM-CHANNEL BLOCKERS [J].
ANGSTADT, JD ;
FRIESEN, WO .
JOURNAL OF NEUROPHYSIOLOGY, 1991, 66 (06) :1858-1873
[4]  
BOOKMAN RJ, 1990, J EXP BIOL, V149, P223
[5]   DIFFERENT VOLTAGE-DEPENDENCE OF TRANSIENT AND PERSISTENT NA+ CURRENTS IS COMPATIBLE WITH MODAL-GATING HYPOTHESIS FOR SODIUM-CHANNELS [J].
BROWN, AM ;
SCHWINDT, PC ;
CRILL, WE .
JOURNAL OF NEUROPHYSIOLOGY, 1994, 71 (06) :2562-2565
[6]   HEARTBEAT CONTROL IN THE MEDICINAL LEECH - A MODEL SYSTEM FOR UNDERSTANDING THE ORIGIN, COORDINATION, AND MODULATION OF RHYTHMIC MOTOR PATTERNS [J].
CALABRESE, RL ;
NADIM, F ;
OLSEN, OH .
JOURNAL OF NEUROBIOLOGY, 1995, 27 (03) :390-402
[7]   ATTACHMENT TO CON-A OR EXTRACELLULAR-MATRIX INITIATES RAPID SPROUTING BY CULTURED LEECH NEURONS [J].
CHIQUET, M ;
ACKLIN, SE .
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA, 1986, 83 (16) :6188-6192
[8]   CS+ LOADING REVEALS NA+-DEPENDENT PERSISTENT INWARD CURRENT AND NEGATIVE SLOPE RESISTANCE REGION IN APLYSIA GIANT-NEURONS [J].
COLMERS, WF ;
LEWIS, DV ;
WILSON, WA .
JOURNAL OF NEUROPHYSIOLOGY, 1982, 48 (05) :1191-1200
[9]  
DAVIS RE, 1988, J NEUROSCI, V8, P3978
[10]   VOLTAGE DEPENDENCE OF 5-HYDROXYTRYPTAMINE RELEASE AT A SYNAPSE BETWEEN IDENTIFIED LEECH NEURONS IN CULTURE [J].
DIETZEL, ID ;
DRAPEAU, P ;
NICHOLLS, JG .
JOURNAL OF PHYSIOLOGY-LONDON, 1986, 372 :191-&