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Activation of chloride current by P2‐purinoceptors in rat ventricular myocytes
Author(s) -
Kaneda M.,
Fukui K.,
Doi K.
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.tb14894.x
Subject(s) - dids , reversal potential , extracellular , pipette , chemistry , biophysics , chloride channel , conductance , purinergic receptor , adenosine , myocyte , chloride , patch clamp , medicine , endocrinology , biochemistry , biology , receptor , membrane , mathematics , combinatorics , organic chemistry
1 Rat ventricular myocytes were dissociated and their responses to extracellularly applied ATP were recorded using patch pipettes under the whole cell configuration. 2 ATP initially induced an inward current followed by an outward current at − 50 mV. With a Cs‐rich pipette solution the late outward current was blocked, leaving a sustained inward current ( I ATPs ) suggesting that a K + conductance underlies the late response. 3 When the extracellular Cl − concentration was changed, the reversal potential of I ATPs corresponded well to the shift of the Cl − equilibrium potential. I ATPs was reversibly blocked by the chloride channel blocker, 4,4′‐diisothiocyanatostilbene‐2,2′‐disulphonic acid (DIDS). 4 The concentration‐response curve of I ATPs had a Hill coefficient of 0.98 and an EC 50 value of 5.2 × 10 −6 m . 5 ATP was more potent than ADP, while AMP and adenosine were ineffective, suggesting that P 2 ‐purinoceptor activation induced I ATPs . 6 The activation of I ATPs was depressed by depleting the extracellular Mg 2+ and increased by adding Mg 2+ . 7 Our results strongly suggest that P 2 ‐purinoceptor activation by ATP induces both a Cl − ‐conductance (I ATPs ) and a K + ‐conductance in rat ventricular myocytes.