MODULATION OF CALCIUM-DEPENDENT AND CALCIUM-INDEPENDENT COMPONENTS OF VERATRIDINE-EVOKED RELEASE OF GLUTAMATE FROM RAT CEREBELLUM

被引:12
作者
DICKIE, BGM [1 ]
DAVIES, JA [1 ]
机构
[1] UNIV WALES COLL MED, DEPT PHARMACOL & THERAPEUT, HEATH PK, CARDIFF CF4 4XN, S GLAM, WALES
关键词
GLUTAMATE; CALCIUM; CEREBELLAR SLICE; VERATRIDINE;
D O I
10.1016/0006-8993(93)91618-3
中图分类号
Q189 [神经科学];
学科分类号
071006 ;
摘要
The entry of Ca2+ into the presynaptic neuronal terminal is considered to be a prerequisite for exocytosis. However, reports suggest that a Ca2+-independent component of release can exist for some neurotransmitters. In this study we have used veratridine-stimulated release of glutamate from rat cerebellar slices to investigate Ca2+-dependent and -independent release. A 1-min pulse of veratridine (10 muM) induced release of glutamate in both Ca2+-replete and Ca2+-free ACSF. Both modes of release, however, could be elicited in a sequential manner following a single application of veratridine in Ca2+-free ACSF, with return to Ca2+-replete conditions 5 min post-pulse. This separation permitted the modulation of either, or both, phases of release. Apamin and dihydrokainate had little effect on Ca2+-independent release but produced enhancement of the Ca2+-dependent phase. Tetrodotoxin abolished both phases of release when applied with the veratridine pulse, but had no effect on the Ca2+-dependent phase alone. The Ca2+-dependent phase was partially sensitive to Co2+, although the Ca2+ channel blockers verapamil, amiloride, omega-conotoxin and ruthenium red were ineffective, suggesting a lack of involvement of L-, N- or T-type channels. The possible mechanisms mediating the Ca2+-dependent and -independent components of endogenous glutamate release from cerebellar slices are discussed.
引用
收藏
页码:247 / 254
页数:8
相关论文
共 55 条
[51]   AMILORIDE SELECTIVELY BLOCKS THE LOW THRESHOLD (T) CALCIUM-CHANNEL [J].
TANG, CM ;
PRESSER, F ;
MORAD, M .
SCIENCE, 1988, 240 (4849) :213-215
[52]  
VANVLIET BJ, 1989, J NEUROCHEM, V52, P1229
[53]   VERATRIDINE-INDUCED RELEASE OF ENDOGENOUS GLUTAMATE FROM RAT-BRAIN CORTEX SLICES - A REAPPRAISAL OF THE ROLE OF CALCIUM [J].
VILLANUEVA, S ;
FRENZ, P ;
DRAGNIC, Y ;
ORREGO, F .
BRAIN RESEARCH, 1988, 461 (02) :377-380
[54]   COMPARTMENTATION OF GLUTAMATE AND ASPARTATE WITHIN CEREBRAL CORTICAL SYNAPTOSOMES - EVIDENCE FOR A NON-CYTOPLASMIC ORIGIN FOR THE CALCIUM-RELEASABLE POOL OF GLUTAMATE [J].
WILKINSON, RJ ;
NICHOLLS, DG .
NEUROCHEMISTRY INTERNATIONAL, 1989, 15 (02) :191-197
[55]   APAMIN DEPRESSES SELECTIVELY THE AFTER-HYPERPOLARIZATION OF CAT SPINAL MOTONEURONS [J].
ZHANG, L ;
KRNJEVIC, K .
NEUROSCIENCE LETTERS, 1987, 74 (01) :58-62