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Mepacrine‐induced inhibition of the inward current mediated by 5‐HT 3 receptors in rat nodose ganglion neurones
Author(s) -
Fan Ping
Publication year - 1994
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.1476-5381.1994.tb13141.x
Subject(s) - mepacrine , receptor , chemistry , pharmacology , endocrinology , medicine , biology , biophysics , biochemistry , immunology , malaria
1 With the whole‐cell patch clamp technique, the effect of the antimalarial drug, mepacrine (quinacrine) on the inward current mediated by 5‐HT 3 receptors (5‐hydroxytryptamine (5‐HT)‐induced current) was investigated in isolated nodose ganglion neurones of the rat. 2 5‐HT and the selective 5‐HT 3 receptor agonists, 2‐methyl‐5‐HT and m ‐chlorophenylbiguanide elicited an inward current which reversed at around 0 mV and quickly desensitized to a steady state level. 3 Mepacrine dose‐dependently inhibited the peak current induced by 5‐HT with an IC 50 of 2.1 μ m and an apparent Hill coefficient of 0.99. 4 Mepacrine increased the decay rate of the 5‐HT‐induced current. 5 The effect of mepacrine on the 5‐HT‐induced current was reversible and not dependent on membrane potential. The reversal potential of the 5‐HT‐induced current was not affected. 6 Intracellular mepacrine had no significant effect on the 5‐HT‐induced current and did not block the extracellular action of mepacrine. 7 Concentration‐response curves in the presence and absence of mepacrine suggest a non‐competitive inhibition of 5‐HT‐induced current by mepacrine.