Gender does not influence neuromuscular properties in dimorphic skeletal muscles of the toad

Gender does not influence neuromuscular properties in dimorphic skeletal muscles of the toad

Autor Lima-Landman, M. T. Google Scholar
Lapa, A. J. Google Scholar
Instituição Universidade Federal de São Paulo (UNIFESP)
Resumo The aim of this work was to study gender differences on the physiology of the dimorphic brachial musculature involved in the clasp reflex of the toad (Bufo marinus L.). the neuromuscular transmission, the sensitivity to acetylcholine (ACh) and the cholinesterase activity were compared on the forelimb sternoradialis muscles (SR) from male and female toads. the interosseous muscles of the first finger were used to compare the properties of the nicotinic receptor/ionic channel complex (AChR). All the muscles studied were dimorphic, i.e. significantly smaller in the female than in the male frog in otherwise similar size animals. the SR of either sex contracted to bath application of ACh with similar EC50. in physiological solution the frequency of the miniature end-plate potentials (mepps) was very low (0.1 s(-1)) and no gender difference was detected. the mepp amplitudes were 0.62 +/- 0.03 and 0.58 +/- 0.03 mV in SR from male and female toads, respectively. To increase exocytosis the muscles were incubated in hypertonic solution (158 mM NaCl). Under this condition mepp frequency was increased by five and seven times and mepp amplitude increased by 1.3 and 1.6 times in SR from male and female toads, respectively. the cholinesterase activity measured by the colorimetric method, did not differ in SR from male and female toads. in muscle fibers dissociated from the dimorphic interosseous muscles of male and female toads, the ionic channel conductance was 43 +/- 5.3 and 44 +/- 4.5 pS, respectively. the mean channel open time was voltage-dependent and not significantly different in preparations from both genders. These observations indicate that neither the ACh-nicotinic receptor interaction, nor the AChR complex kinetics and the nicotinic excitation-contraction coupling or the cholinesterase activity differ in dimorphic muscles from Bufo genders. No gender difference was detected in neuromuscular transmission of the studied muscle. Only a slight increase in mepp frequency and amplitude could be detected when the muscles were incubated in hypertonic solution. (C) 1998 Elsevier Science Inc. All rights reserved.
Palavra-chave acetylcholine nicotinic receptors
neuromuscular junction
clasp muscles
synaptic transmission
patch-clamp technique
Idioma Inglês
Data de publicação 1998-10-01
Publicado em Comparative Biochemistry and Physiology A-molecular and Integrative Physiology. New York: Elsevier B.V., v. 121, n. 2, p. 119-126, 1998.
ISSN 1095-6433 (Sherpa/Romeo, fator de impacto)
Publicador Elsevier B.V.
Extensão 119-126
Direito de acesso Acesso restrito
Tipo Artigo
Web of Science WOS:000077246200003
Endereço permanente

Exibir registro completo


Arquivo Tamanho Formato Visualização

Não existem arquivos associados a este item.

Este item está nas seguintes coleções



Minha conta