Electrophysiological activity of the C-peptide of the Locusta insulin-related peptide. Effect on the membrane conductance of Locusta neurones in vitro.
FEBS Lett
; 293(1-2): 137-41, 1991 Nov 18.
Article
em En
| MEDLINE
| ID: mdl-1959647
ABSTRACT
The C-peptide of Locusta insulin-related peptide, which is a 50 residue peptide originally isolated from the corpora cardiaca of the insect Locusta migratoria and to which we refer as 5-kDa peptide, has been synthesised chemically by the solid-phase method, using a BOC strategy. Since this peptide contains in its sequence a potential monobasic cleavage site, we also synthesised its 1-38 residue-related fragment, named 4-kDa peptide, although we have no hints of its natural occurrence in the corpora cardiaca. Electrophysiological studies have shown that both the 5-kDa and 4-kDa peptides depolarise the membrane and increase the membrane conductance of neurones freshly isolated from the thoracic ganglia of Locusta. Under voltage-clamp conditions, the current underlying these effects was inwardly directed and could be resolved into 2 components. One component, I(5-kDa)1, activated at potentials more hyperpolarised than -50 mV, peaked at about -75 mV and was blocked by the potassium channel blockers cesium and rubidium. The second component, I(5-kDa)2 was activated at potentials more depolarised than -50 mV, increased with depolarisation and was not blocked by cesium and rubidium. The effects of the 5-kDa and 4-kDa peptides on the membrane potential and membrane conductance of Locusta neurones suggest that these peptides may have a physiological role in the central nervous system of insects.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Neuropeptídeos
/
Peptídeo C
/
Gafanhotos
/
Potenciais da Membrana
Limite:
Animals
Idioma:
En
Revista:
FEBS Lett
Ano de publicação:
1991
Tipo de documento:
Article
País de afiliação:
Reino Unido