A nematode FMRFamide-like peptide, SDPNFLRFamide (PF1), relaxes the dorsal muscle strip preparation of Ascaris suum.
Parasitology
; 108 ( Pt 2): 229-36, 1994 Feb.
Article
en En
| MEDLINE
| ID: mdl-8159468
PF1 (SDPNFLRFamide) is a FMRFamide-like peptide extracted from the free-living nematode Panagrellus redivivus. Here we show that this peptide causes a hyperpolarization of somatic muscle cells of the parasitic nematode Ascaris suum and a relaxation of the somatic muscle strip preparation. We have assessed whether or not the relaxation of Ascaris dorsal muscle strip by PF1 is due to (i) inhibition of the release of the excitatory neuromuscular junction transmitter acetylcholine (ACh), (ii) potentiation of the release of the inhibitory neuromuscular junction transmitter gamma-aminobutyric acid (GABA) or (iii) a direct inhibitory action of the peptide on the muscle cells. Under the experimental conditions described here, tonic ACh release does not seem to be involved in determining the resting membrane potential or resting tone of the Ascaris dorsal muscle strip and thus inhibition of tonic ACh release is unlikely to explain the relaxation elicited by the peptide. Furthermore, PF1 (100 nM-1 microM) inhibited the contraction of the muscle strip elicited by bath application of ACh, suggesting either a direct inhibitory action of the peptide on the muscle cells or a potentiation of GABA release. In electrophysiological experiments, the reversal potential for the PF1 hyperpolarization was not the same as that for GABA. Thus, PF1 hyperpolarizes Ascaris muscle by a mechanism that does not involve stimulation of GABA release from inhibitory pre-synaptic terminals.
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Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Neuropéptidos
/
Proteínas del Helminto
/
Rabdítidos
/
Ascaris suum
/
FMRFamida
Límite:
Animals
Idioma:
En
Revista:
Parasitology
Año:
1994
Tipo del documento:
Article
Pais de publicación:
Reino Unido