5-Hydroxytryptamine releases adenosine 5'-triphosphate from nerve varicosities isolated from the myenteric plexus of guinea-pig ileum

M. Al-Humayyd, T. D. White

Research output: Contribution to journalArticlepeer-review

15 Citations (Scopus)

Abstract

1. 5-Hydroxytryptamine (5-HT)-evoked release of ATP from nerve varicosities isolated from the myenteric plexus of guinea pig ileum was investigated. 2. 5-HT released ATP from myenteric varicosities by a Ca2+-dependent mechanism. The EC50 for release of ATP was 7 x 10-7 M 5-HT. 3. 5-HT-evoked release of ATP was not blocked by tetrodotoxin (TTX), indicating that release was not initiated by the opening of Na+-channels in the isolated myenteric varicosities. 4. Release of ATP by 5-HT was diminished to 56% of control values by in vivo pretreatment of the guinea-pig with 6-hydroxydopamine (6-OHDA, 250 mg kg-1, i.p.) for 24 h. 6-OHDA pretreatment caused extensive destruction of noradrenergic varicosities as indicated by an 87% loss of noradrenaline content. 5. Quipazine (5 x 10-6 M) and methysergide (10-4 M) caused a small release of ATP and blocked subsequent 5-HT-induced release of ATP. Metergoline (2.5 x 10-5 M), (+)-tubocurarine (7 x 10-5 M) and cocaine (10-4 M) decreased 5-HT-induced ATP release. 5-Methoxytryptamine (10-4 M), picrotoxin (3.5 x 10-6 M), spiroperidol (10-6 M), morphine (1.3 x 10-6 M) and phenoxybenzamine (3.7 x 10-7 M) were ineffective. 6. The results demonstrate a 5-HT-receptor-mediated release of ATP from noradrenergic and possibly non-adrenergic varicosities in the myenteric plexus of guinea-pig ileum. The 5-HT-induced release of ATP is consistent with a possible transmitter, cotransmitter or modulatory role for ATP in the myenteric plexus.

Original languageEnglish
Pages (from-to)27-34
Number of pages8
JournalBritish Journal of Pharmacology
Volume84
Issue number1
Publication statusPublished - 1985

ASJC Scopus Subject Areas

  • Pharmacology

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