Effects of sulphydryl reagents on an insect nerve-muscle preparation

T. A. Bratkowski, T. J. McDonald, R. D. O'Brien

Research output: Contribution to journalArticle

2 Scopus citations

Abstract

The sulphydryl inhibitors N-ethyl maleimide (NEM), iodoacetic acid (IAA), p-chloromercuribenzoic acid (PCMB), and mersalyl at concentrations in the millimolar range blocked the neurally evoked mechanical response of an isolated nerve-muscle preparation from the grasshopper, Romalea microptera, and also blocked the contractions evoked by external application of l-glutamic acid, the suspected excitatory neurotransmitter. Blockade caused by PCMB could be reversed completely by post-perfusion with dithiothreitol (DTT); however, that caused by mersalyl was irreversible. Protection could be achieved by prior mixture of inhibitors with equimolar concentrations of the thiols, l-cysteine or reduced glutathione. The alkylating agents NEM and IAA also reduced the retractor unguis contracture caused by depolarization with high K+ saline, whereas the organomercurials PCMB and mersalyl did not. The primary site of action appears to be the post-synaptic membrane. These findings indicate significant differences from the response of the eel electroplax preparation and suggest a functional rôle for free sulphydryl groups rather than disulphide linkages in this insect excitatory neuromuscular junction.

Original languageEnglish (US)
Pages (from-to)1949-1955,1957-1960
JournalJournal of Insect Physiology
Volume18
Issue number10
DOIs
StatePublished - Oct 1972
Externally publishedYes

ASJC Scopus subject areas

  • Physiology
  • Insect Science

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