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Titolo:
EFFECTS OF LANTHANUM AT SNAKE TWITCH AND TONIC MUSCLE-FIBER END-PLATES
Autore:
CONIGLIO LM; HENDRICKS GM; PARSONS RL;
Indirizzi:
UNIV VERMONT,COLL MED,DEPT ANAT & NEUROBIOL BURLINGTON VT 05405
Titolo Testata:
Journal of physiology
, volume: 466, anno: 1993,
pagine: 405 - 419
SICI:
0022-3751(1993)466:<405:EOLAST>2.0.ZU;2-D
Fonte:
ISI
Lingua:
ENG
Soggetto:
FROG NEUROMUSCULAR-JUNCTIONS; IONS; ACETYLCHOLINE; DESENSITIZATION; POTENTIALS; TERMINALS;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
22
Recensione:
Indirizzi per estratti:
Citazione:
L.M. Coniglio et al., "EFFECTS OF LANTHANUM AT SNAKE TWITCH AND TONIC MUSCLE-FIBER END-PLATES", Journal of physiology, 466, 1993, pp. 405-419

Abstract

1. The effects of 1 mm lanthanum on miniature endplate current (MEPC)frequency, amplitude, and decay time course were studied in voltage-clamped twitch and tonic muscle fibres in the garter snake, Thamnophis.2. Lanthanum produced a marked increase in MEPC frequency in both fibre types. The maximum frequency in lanthanum was greater at twitch endplates than at tonic endplates although the increase in frequency relative to control levels was as great in tonic fibres as in twitch fibres. 3. In twitch fibres continually exposure to lanthanum, the frequency of MEPCs reached a peak value and then declined progressively until,after approximately 6 h, no MEPCs were recorded. In contrast, at tonic endplates exposed to 1 mm lanthanum, MEPC frequency remained elevated above control levels for periods greater than 20 h. 4. Lanthanum decreased the mean amplitude of MEPCs, skewed the amplitude distribution and increased MEPC duration at both twitch and tonic fibre endplates. 5. Ultrastructural analysis showed that after a 15 min exposure to 1 mm lanthanum, approximately half of the boutons innervating a twitch fibre contained fewer synaptic vesicles than boutons at control endplates, whereas nerve terminals innervating tonic fibre endplates were similar in appearance to those in control preparations. At endplates on both fibres, the postsynaptic membrane was more electron dense than thatof control preparations. 6. Following a 6 h exposure to lanthanum, all nerve terminals innervating twitch endplates contained only a few synaptic vesicles and numerous intracellular deposits of electron dense material. The nerve terminals innervating tonic endplates still contained many synaptic vesicles, but the number appeared to be less than that of tonic terminals in untreated preparations. 7. The results demonstrate that lanthanum stimulates spontaneous quantal transmitter release from nerve terminals innervating either twitch or tonic fibres. However, the terminals innervating twitch fibres become depleted of synaptic vesicles, whereas this does not occur as readily in nerve terminalsinnervating tonic fibres.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 30/11/20 alle ore 16:29:13