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Activation by ATP of a P 2U ‘nucleotide’ receptor in an exocrine cell
Author(s) -
Martin Shaun C.,
Shuttleworth Trevor J.
Publication year - 1995
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.1476-5381.1995.tb15880.x
Subject(s) - p2 receptor , p2y receptor , nucleotide , extracellular , adenosine triphosphate , adenosine , biophysics , receptor , membrane potential , chemistry , purinergic receptor , biology , biochemistry , medicine , endocrinology , gene
1 We employed the perforated patch whole‐cell technique to investigate the effects of ATP and other related nucleotides on membrane conductances in avian exocrine salt gland cells. 2 ATP (10μ m ‐1 mM) evoked an increase in maxi‐K + and Cl − conductances with a reversal potential of −35mV. At lower concentrations of ATP (≤100 μ m ) responses were generally oscillatory with a sustained response observed at higher concentrations (≥200 μ m ). 3 Both oscillatory and sustained responses were abolished by the removal of bath Ca 2+ . In cells preincubated in extracellular saline containing reduced Ca 2+ , the application of ATP resulted in a transient increase in current. 4 As increasing concentrations of ATP (and related nucleotides) evoked a graded sequence of events with little run‐down we were able to establish a rank order of potency in single cells. The order of potency of ATP analogues and agonists of the various P 2 ‐receptor subtypes was UTP>ATP = 2‐methylthio‐ATP>ADP. Adenosine (1μ m ‐1m m ), AMP (1μ m ‐1μ m ), α,β‐methylene‐ATP (1 μ M −1 m m ) and α,β‐methylene‐ATP (1μ m ‐ m m ) were without effect. 5 In conclusion, although unable to preclude a role for a P 2Y ‐receptor, our results suggest that ATP binds to a P 2U ‐receptor increasing [Ca 2+ ] i and subsequently activating Ca 2+ ‐sensitive K + and Cl − currents.