Distinct endothelin-B receptors mediate the effects of sarafotoxin S6c and IRL1620 in the ileum

Distinct endothelin-B receptors mediate the effects of sarafotoxin S6c and IRL1620 in the ileum

Author Miasiro, N. Autor UNIFESP Google Scholar
Karaki, H. Google Scholar
Paiva, ACM Autor UNIFESP Google Scholar
Institution Universidade Federal de São Paulo (UNIFESP)
Univ Tokyo
Abstract In the guinea pig ileum, both sarafotoxin S6c (S6c) and IRL1620 induced a biphasic effect (relaxation and contraction). S6c induced strong tachyphylaxis of both components of the response, but IRL1620 induced tachyphylaxis mainly of the contractile component. Whereas the tissues rendered tachyphylactic to S6c did not respond to IRL1620, a normal biphasic response to S6c was observed in the tissues rendered tachyphylactic to IRL1620. in the presence of IRL1620, S6c could induce its biphasic effect, whereas in the presence of S6c, IRL1620 was ineffective. BQ-123, a specific ETA antagonist, did not affect the biphasic response induced by either agonist. PD145065, a potent ETA/ETB antagonist, was a competitive and a noncompetitive antagonist, respectively, of the contractile components of IRL1620 and S6c. RES-701-1, a specific ETB1 antagonist, inhibited both components of the response induced by IRL1620. However, it inhibited mainly the relaxant component induced by low doses of S6c. Apamin had different effects on endothelin-1 (ET-1), S6c, and IRL1620. Our results suggest that there are at least two distinct populations of ETB receptors mediating the biphasic response: the ETB1 receptor, sensitive to RES-701-1 and PD145065, and the ETB2 receptor, less sensitive to RES-701-1 and PD145065.
Keywords sarafotoxin S6c
IRL1620
ileum (guinea pig)
endothelin receptor subtypes
tachyphylaxis
Language English
Date 1998-01-01
Published in Journal of Cardiovascular Pharmacology. Philadelphia: Lippincott Williams & Wilkins, v. 31, p. S175-S178, 1998.
ISSN 0160-2446 (Sherpa/Romeo, impact factor)
Publisher Lippincott Williams & Wilkins
Extent S175-S178
Origin http://dx.doi.org/10.1097/00005344-199800001-00050
Access rights Open access Open Access
Type Article
Web of Science ID WOS:000174051600050
URI http://repositorio.unifesp.br/handle/11600/25834

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