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Non‐additive interaction between nicotinic cholinergic and P2X purine receptors in guinea‐pig enteric neurons in culture
Author(s) -
Zhou Xiaoping,
Galligan James J.
Publication year - 1998
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1111/j.1469-7793.1998.685ba.x
Subject(s) - acetylcholine , nicotinic agonist , receptor , cholinergic , chemistry , acetylcholine receptor , reversal potential , p2y receptor , biophysics , agonist , patch clamp , medicine , endocrinology , biology , biochemistry
1 Acetylcholine (ACh)‐activated currents and their interaction with ATP‐activated currents were studied in primary cultures of myenteric neurons from guinea‐pig small intestine using patch clamp techniques. Peak currents caused by co‐application of ACh (1 m m ) and ATP (300 μ m ) were 78 ± 2 % of the sum of currents activated by each agonist alone ( P < 0.05, n = 29 ). Reversal potentials measured during co‐application of ACh and ATP did not differ from those measured during application of ACh or ATP alone. Addition of BAPTA (10 m m ) to the pipette solution or replacement of extracellular Ca 2+ with Na + did not prevent occlusion. 2 Responses caused by co‐application of 5‐HT (300 μ m ), acting at 5‐HT 3 receptors, and ACh (3 m m ) or ATP (1 m m ) were additive (94 ± 3 or 96 ± 4 %, respectively, of the sum of currents activated by 5‐HT and ACh or ATP alone; P > 0.05 ). Currents caused by GABA (1 m m ), acting at GABA A receptors, and ACh (3 m m ) or ATP (1 m m ) were also additive (105 ± 4 or 100 ± 3 %, respectively, of the sum of currents activated by GABA and ACh or GABA and ATP applied separately; P > 0.05 ). 3 Single channel currents caused by ACh and ATP in the same outside‐out patches were less than additive (85 ± 10 % of the predicted sum, P < 0.05 ). 4 P2X receptors and nicotinic cholinergic receptors (nAChRs) are linked in a mutually inhibitory manner in guinea‐pig myenteric neurons. The functional interaction does not involve ligand binding sites, Ca 2+ ‐dependent mechanisms, a change in the driving force for Na + or cytoplasmic signalling mechanisms.