QUANTAL TRANSMITTER RELEASE MEDIATED BY STRONTIUM AT THE MOUSE MOTOR-NERVE TERMINAL

被引:34
作者
BAIN, AI [1 ]
QUASTEL, DMJ [1 ]
机构
[1] UNIV BRITISH COLUMBIA, FAC MED, DEPT PHARMACOL & THERAPEUT, 2176 HLTH SCI MALL, VANCOUVER V6T 1W5, BC, CANADA
来源
JOURNAL OF PHYSIOLOGY-LONDON | 1992年 / 450卷
关键词
D O I
10.1113/jphysiol.1992.sp019116
中图分类号
Q189 [神经科学];
学科分类号
071006 ;
摘要
1. In isolated mouse diaphragm, nerve stimulation in the presence of Sr2+ evokes phasic quantal transmitter release (endplate potentials, EPPs) with the same time course as in the presence of Ca2+. 2. Brief tetanic trains of nerve stimuli in the presence of Sr2+ cause an increase in quantal content of EPPs accompanied by an increase in the frequency of miniature EPPs (MEPPs); the latter persists as a 'tail' that subsides within about a second. Pseudo-random stimulation sequences were used to characterize these changes. 3. The fourth root of MEPP frequency during or after stimulation rose and fell in accordance with first order kinetics with the same time constants for rising and falling phases, in agreement with a 'residual ion' model in which (a) each nerve impulse causes the same entry of Sr2+ into the nerve terminal, (b) transmitter release MEPP frequency) is proportional to the fourth power of [Sr2+] at release sites, and (c) Sr2+ removal is a first order process with a time constant of about 250 ms. 4. After exposure to bis (O-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid, acetoxymethyl ester form (BAPTA AM), 'Sr2+ tails' of MEPP frequency were reduced in magnitude and prolonged. 5. During stimulation trains, growth of phasic transmitter release rates (and quantal content of EPPs) were related to growth of MEPP frequency in almost exact agreement with a residual ion model, in which 'phasic' release (EPPs) and MEPP frequency are governed by the same equation, with the same parameters, and without any effect of depolarization per se to affect phasic release. 6. Prolonged (1 s) nerve terminal depolarizations in the presence of Sr2+ produce increased MEPP frequency with a time course correponding to a model in which depolarization per se has little or no effect to increase transmitter release. 7. It was concluded that in the presence of Sr2+ the intense 'phasic' acceleration of quantal release induced by nerve impulse manifest in an EPP can be attributed to a transient rise of intracellular [Sr2+] in the vicinity of release sites, while the modulation of 'phasic' release by antecedent nerve impulses can be attributed to residual Sr2+ which is also manifest in a rise in MEPP frequency.
引用
收藏
页码:63 / 87
页数:25
相关论文
共 34 条
[1]   CALCIUM ACTION IN SYNAPTIC TRANSMITTER RELEASE [J].
AUGUSTINE, GJ ;
CHARLTON, MP ;
SMITH, SJ .
ANNUAL REVIEW OF NEUROSCIENCE, 1987, 10 :633-693
[2]   ESTIMATING THE TIME COURSE OF EVOKED QUANTAL RELEASE AT THE FROG NEUROMUSCULAR-JUNCTION USING END-PLATE CURRENT LATENCIES [J].
BALDO, GJ ;
COHEN, IS ;
VANDERKLOOT, W .
JOURNAL OF PHYSIOLOGY-LONDON, 1986, 374 :503-513
[3]   QUANTAL INDEPENDENCE AND UNIFORMITY OF PRESYNAPTIC RELEASE KINETICS AT FROG NEUROMUSCULAR JUNCTION [J].
BARRETT, EF ;
STEVENS, CF .
JOURNAL OF PHYSIOLOGY-LONDON, 1972, 227 (03) :665-689
[4]   KINETICS OF TRANSMITTER RELEASE AT FROG NEUROMUSCULAR JUNCTION [J].
BARRETT, EF ;
STEVENS, CF .
JOURNAL OF PHYSIOLOGY-LONDON, 1972, 227 (03) :691-708
[5]   ROLE OF PRE-SYNAPTIC CALCIUM-IONS AND CHANNELS IN SYNAPTIC FACILITATION AND DEPRESSION AT THE SQUID GIANT SYNAPSE [J].
CHARLTON, MP ;
SMITH, SJ ;
ZUCKER, RS .
JOURNAL OF PHYSIOLOGY-LONDON, 1982, 323 (FEB) :173-193
[6]   TRANSMITTER RELEASE BY MAMMALIAN MOTOR-NERVE TERMINALS IN RESPONSE TO FOCAL POLARIZATION [J].
COOKE, JD ;
QUASTEL, DMJ .
JOURNAL OF PHYSIOLOGY-LONDON, 1973, 228 (02) :377-405
[7]   CUMULATIVE AND PERSISTENT EFFECTS OF NERVE TERMINAL DEPOLARIZATION ON TRANSMITTER RELEASE [J].
COOKE, JD ;
QUASTEL, DMJ .
JOURNAL OF PHYSIOLOGY-LONDON, 1973, 228 (02) :407-434
[8]   PHASIC SECRETION OF ACETYLCHOLINE AT A MAMMALIAN NEUROMUSCULAR-JUNCTION [J].
DATYNER, NB ;
GAGE, PW .
JOURNAL OF PHYSIOLOGY-LONDON, 1980, 303 (JUN) :299-314
[9]   BIOPHYSICAL ASPECTS OF NEURO-MUSCULAR TRANSMISSION [J].
DELCASTILLO, J ;
KATZ, B .
PROGRESS IN BIOPHYSICS & MOLECULAR BIOLOGY, 1956, 6 :122-&
[10]   CO-OPERATIVE ACTION OF CALCIUM IONS IN TRANSMITTER RELEASE AT NEUROMUSCULAR JUNCTION [J].
DODGE, FA ;
RAHAMIMO.R .
JOURNAL OF PHYSIOLOGY-LONDON, 1967, 193 (02) :419-&