The neuropeptide Phe-Met-Arg-Phe-NH2 (FMRFamide) increases levels of inositol 1,4,5-trisphosphate in the tentacle retractor muscle of Helix aspersa.
Exp Physiol
; 78(6): 757-66, 1993 Nov.
Article
en En
| MEDLINE
| ID: mdl-8311943
The C3 neurone, which acts as a motoneurone for the tentacle retractor muscle in Helix aspersa, contains both Phe-Met-Arg-Phe-NH2 (FMRFamide) and acetylcholine (ACh). Each of these transmitter substances evokes contraction of the isolated muscle. FMRFamide induces a delayed rise in tension followed by phasic contractions. Unlike the response to ACh, this response is not associated with a depolarization of the muscle cells. Here we show that FMRFamide stimulates the inositol phosphate second messenger system in the muscle and causes a significant increase in total inositol trisphosphate (InsP3) levels. The isomer which releases intracellular Ca2+ stores, inositol 1,4,5-trisphosphate (Ins(1,4,5)P3), is increased in a similar proportion to the total InsP3. The production of Ins(1,4,5)P3 is therefore likely to be involved in the response of the muscle to FMRFamide and may account for the oscillatory nature of the mechanical response. The N-terminally extended heptapeptide pGlu-Asp-Pro-Phe-Leu-Arg-Phe-NH2 (pQDPFLRFamide), which relaxes the muscle, had no acute effect on InsP3 levels. Indirect evidence also indicates that intracellular Ca2+ stores are required for the generation of the FMRFamide response.
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Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Neuropéptidos
/
Inositol 1,4,5-Trifosfato
/
Caracoles Helix
/
Músculos
Límite:
Animals
Idioma:
En
Revista:
Exp Physiol
Asunto de la revista:
FISIOLOGIA
Año:
1993
Tipo del documento:
Article
País de afiliación:
Reino Unido
Pais de publicación:
Reino Unido