Premium
Neuromuscular blocking agents inhibit receptor‐mediated increases in the potassium permeability of intestinal smooth muscle
Author(s) -
Gater P.R.,
Haylett D.G.,
Jenkinson D.H.
Publication year - 1985
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/j.1476-5381.1985.tb11108.x
Subject(s) - apamin , bradykinin , medicine , pharmacology , endocrinology , guanethidine , receptor , chemistry , biology , stimulation , potassium channel
1 The neuromuscular blocking agents tubocurarine, atracurium and pancuronium have been tested for their ability to inhibit receptor‐mediated increases in the K + permeability of intestinal smooth muscle. 2 All three agents, as well as the bee venom peptide apamin, reduced both the resting efflux of 86 Rb and the increase in efflux caused by the application of either bradykinin (1 μM) or an α 1 ‐adrenoceptor agonist, amidephrine (20 μM), to depolarized strips of guinea‐pig taenia caeci. This suggested that, like apamin, the neuromuscular blocking agents inhibit the Ca 2+ ‐dependent K + permeability (P K(Ca) ) mechanism which in this tissue is activated by a variety of membrane receptors. 3 The concentrations (IC 50 s) of atracurium, pancuronium and (+)‐tubocurarine which reduced the effect of amidephrine on 86 Rb efflux by 50% were 12, 37 and 67 μM respectively. 4 Also in keeping with an ability to block P K(Ca) , the neuromuscular blockers and apamin reduced the inhibition by amidephrine and bradykinin of physalaemin‐mediated contractions of the taenia caeci. The IC 50 values were 15, 31 and 120 μM for atracurium, tubocurarine and pancuronium respectively, and 2.3 nM for apamin. 5 Each of the neuromuscular blockers, and apamin, increased the spontaneous contractions of the rabbit duodenum and blocked the inhibitory effect of amidephrine thereon. 6 It is concluded that the P K(Ca) mechanism in the longitudinal smooth muscle of the intestine resembles that of hepatocytes and sympathetic ganglion cells in its susceptibility to inhibition by neuromuscular blocking agents, as well as by apamin.