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Extracellular ATP‐induced calcium channel inhibition mediated by P1/P2Y purinoceptors in hamster submandibular ganglion neurons
Author(s) -
Abe Mitsuhiro,
Endoh Takayuki,
Suzuki Takashi
Publication year - 2003
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 - 10.1038/sj.bjp.0705174
Subject(s) - ppads , suramin , adenosine , extracellular , purinergic receptor , adenosine triphosphate , p2y receptor , uridine triphosphate , biology , medicine , endocrinology , chemistry , biophysics , biochemistry , receptor , nucleotide , gene
The presence and profile of purinoceptors in neurons of the hamster submandibular ganglion (SMG) have been studied using the whole‐cell configuration of the patch‐clamp technique. Extracellular application of adenosine 5′‐triphosphate (ATP) reversibly inhibited voltage‐dependent Ca 2+ channel (VDCC) currents ( I Ca ) via G i/o ‐protein in a voltage‐dependent manner. Extracellular application of uridine 5′‐triphosphate (UTP), 2‐methylthioATP (2‐MeSATP), α , β ‐methylene ATP ( α , β ‐MeATP) and adenosine 5′‐diphosphate (ADP) also inhibited I Ca . The rank order of potency was ATP=UTP>ADP>2‐MeSATP= α , β ‐MeATP. The P2 purinoceptor antagonists, suramin and pyridoxal‐5‐phosphate‐6‐azophenyl‐2′, 4′‐disulfonic acid (PPADS), partially antagonized the ATP‐induced inhibition of I Ca , while coapplication of suramin and the P1 purinoceptor antagonist, 8‐cyclopentyl‐1,3‐dipropylxanthine (DPCPX), virtually abolished I Ca inhibition. DPCPX alone partially antagonized I Ca inhibition. Suramin antagonized the UTP‐induced inhibition of I Ca , while DPCPX had no effect. Extracellular application of adenosine (ADO) also inhibited I Ca in a voltage‐dependent manner via G i/o ‐protein activation. Mainly N‐ and P/Q‐type VDCCs were inhibited by both ATP and ADO via G i/o ‐protein βγ subunits in seemingly convergence pathways.British Journal of Pharmacology (2003) 138 , 1535–1543. doi: 10.1038/sj.bjp.0705174