Imperial College London


Faculty of MedicineDepartment of Medicine

Honorary Clinical Senior Lecturer



+44 (0)20 3311 7042b.seemungal




Miss Lorna Stevenson +44 (0)20 3313 5525




10L17Lab BlockCharing Cross Campus






BibTex format

author = {Elliott, P and Seemungal, BM and Wallis, DI},
journal = {Naunyn Schmiedebergs Arch Pharmacol},
pages = {503--509},
title = {Antagonism of the effects of 5-hydroxytryptamine on the rabbit isolated vagus nerve by BRL 43694 and metoclopramide.},
url = {},
volume = {341},
year = {1990}

RIS format (EndNote, RefMan)

AB - Depolarization and reduction in the C fibre compound action potential (C spike) in response to 5-HT were recorded simultaneously from rabbit isolated vagus nerve. 5-HT (0.1-100 mumol/l) was applied cumulatively and EC50 and IC50 values measured from individual concentration-response curves. Blockade of 5-HT responses by the 3-indazole carboxamide, BRL 43694, was investigated and compared with the blocking action of metoclopramide. BRL 43694 was a selective antagonist of 5-HT responses. A concentration of 10 nmol/l BRL 43694, which nearly abolished the depolarization and reduction of the C spike evoked by 5-HT (100 mumol/l), had no effect on similar responses evoked by DMPP (100 mumol/l) or GABA (100 mumol/l). Blockade of 5-HT responses by BRL 43694 (0.3 nmol/l) was slow in onset, a plateau blockade occurring after equilibrium of tissue with antagonist for 2 to 3 h. Metoclopramide induced a blockade of rapid onset. The maximal blockade was apparent within 30 min of application. Full recovery in the responsiveness of the tissue to 5-HT was observed within 30 min of washing out metoclopramide. BRL 43694 at concentrations of 0.3, 1, 3 and 10 nmol/l caused a progressive rightward shift of the concentration-response curves to 5-HT. At the highest concentration of antagonist, there was some depression of the maximal 5-HT response. The apparent pA2 estimated from the Schild equation was 10.03 +/- 0.09 (mean +/- SEM, n = 20) against 5-HT depolarization and 10.31 +/- 0.1 against C spike reduction. Schild plots had slopes not significantly different from 1.0.(ABSTRACT TRUNCATED AT 250 WORDS)
AU - Elliott,P
AU - Seemungal,BM
AU - Wallis,DI
EP - 509
PY - 1990///
SN - 0028-1298
SP - 503
TI - Antagonism of the effects of 5-hydroxytryptamine on the rabbit isolated vagus nerve by BRL 43694 and metoclopramide.
T2 - Naunyn Schmiedebergs Arch Pharmacol
UR -
VL - 341
ER -