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Titolo:
Effects of adenosine on Ca2+ entry in the nerve terminal of the frog neuromuscular junction
Autore:
Robitaille, R; Thomas, S; Charlton, MP;
Indirizzi:
Univ Montreal, Ctr Rech Sci Neurol, Dept Physiol, Montreal, PQ H3C 3J7, Canada Univ Montreal Montreal PQ Canada H3C 3J7 ol, Montreal, PQ H3C 3J7, Canada Univ Toronto, Dept Physiol, MRC, Grp Nerve Cells & Synapses, Toronto, ON M5S 1A8, Canada Univ Toronto Toronto ON Canada M5S 1A8 apses, Toronto, ON M5S 1A8, Canada
Titolo Testata:
CANADIAN JOURNAL OF PHYSIOLOGY AND PHARMACOLOGY
fascicolo: 9, volume: 77, anno: 1999,
pagine: 707 - 714
SICI:
0008-4212(199909)77:9<707:EOAOCE>2.0.ZU;2-S
Fonte:
ISI
Lingua:
ENG
Soggetto:
QUANTAL TRANSMITTER RELEASE; PERISYNAPTIC SCHWANN-CELLS; CALCIUM CHANNELS; GLIAL-CELLS; INTRACELLULAR CALCIUM; SYNAPTIC TRANSMISSION; POTASSIUM CHANNELS; PROTEIN-KINASE; ENDINGS; ACETYLCHOLINE;
Keywords:
adenosine; Ca2+; nerve terminal; transmitter release; synaptic depression;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Life Sciences
Citazioni:
32
Recensione:
Indirizzi per estratti:
Indirizzo: Robitaille, R Univ Montreal, Ctr Rech Sci Neurol, Dept Physiol, POB 6128,Stn Ctr Ville, Montreal, PQ H3C 3J7, Canada Univ Montreal POB 6128,Stn Ctr Ville Montreal PQ Canada H3C 3J7
Citazione:
R. Robitaille et al., "Effects of adenosine on Ca2+ entry in the nerve terminal of the frog neuromuscular junction", CAN J PHYSL, 77(9), 1999, pp. 707-714

Abstract

This study aimed to test whether nerve-evoked and adenosine-induced synaptic depression are due to reduction in Ca2+ entry in nerve terminals of the frog neuromuscular junction. Nerve terminals were loaded with the fluorescent Ca2+ indicator fluo 3 (fluo 3-AM) or loaded with dextran-coupled Ca2+ green-1 transported from the cut end of the nerve. Adenosine (10-50 mu M) didnot change the resting level of Ca2+ in the presynaptic terminal, whereas it induced large Ca2+ responses in perisynaptic Schwann cells, indicating that adenosine was active and might have induced changes in the level of Ca2 in the nerve terminal. Ca2+ responses in nerve terminals could be inducedby nerve stimulation (0.5 or 100 Hz for 100 ms) over several hours. In thepresence of adenosine (10 mu M), the size and duration of the nerve-evokedCa2+ responses were unchanged. When extracellular Ca2+ concentration was lowered to produce the same reduction in transmitter release as the application of adenosine, Ca2+ responses induced by nerve stimulations were reducedby 40%. This indicates that changes in Ca2+ responsible for the decrease in release should have been detected if the mechanism of adenosine depression involved partial block of Ca2+ influx. Ca2+ responses evoked by prolongedhigh frequency trains of stimuli (50 Hz for 10 or 30 s), which caused profound depression of transmitter release, were sustained during the whole duration of the stimulation, and adenosine had no effect on these responses. These data indicate that neither adenosine induced synaptic depression nor stimulation-induced synaptic depression are caused by reductions in Ca2+ entry into the presynaptic terminal in the frog neuromuscular junction.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 12/07/20 alle ore 03:04:51