Effects of P2-purinoceptor antagonists on ecto-nucleotidase activity of guinea-pig vas deferens cultured smooth muscle cells.
Ecto-nucleotidase activity was studied on primary cultures of guinea-pig vas deferens smooth muscle cells by measuring the inorganic phosphate (Pi) production using ATP as a substrate. The ecto-nucleotidase was insensitive to ouabain, oligomycin, sodium azide, p-nitrophenyl phosphate and B-glycerophosphate. Enzyme activity was highly dependent on either Ca2+ or Mg2+. Antagonists of P2X-purinoceptors, pyridoxalphosphate-6-azophenyl-2',4'- disulphonic acid, 4'4'-diisothiocyanatostilbene-2'2'- disulphonate, suramin and pyridoxal-5-phosphate, significantly inhibited ecto-nucleotidase activity. In contrast, the P1-purinoceptor antagonists, 8-p-sulphophenyl theophylline and 1,3-dipropyl-8-cyclopentylxanthine, did not affect the enzyme activity. Thus, when P2-purinoceptors are studied by testing agonists and antagonists potencies, the inhibition of ecto-nucleotidase activity by currently available P2-purinoceptor antagonists should be taken into account.
Department of Anatomy and Developmental Biology, University College London, UK.
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Ziganshin
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Ziganshina
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Bodin
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D
Bailey
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Burnstock
D000251:Adenosine Triphosphatases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D002118:Calcium / Q000494:pharmacology; D002478:Cells, Cultured; D004492:Edetic Acid / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D006168:Guinea Pigs; D007700:Kinetics; D008274:Magnesium / Q000494:pharmacology; D008297:Male; D009130:Muscle, Smooth / Q000201:enzymology*; D010710:Phosphates / Q000378:metabolism; D058919:Purinergic P2 Receptor Antagonists; D012265:Ribonucleotides / Q000378:metabolism; D013329:Structure-Activity Relationship; D013379:Substrate Specificity; D014649:Vas Deferens / Q000201:enzymology*
D004791:Enzyme Inhibitors; D010710:Phosphates; D058919:Purinergic P2 Receptor Antagonists; D012265:Ribonucleotides; D000255:Adenosine Triphosphate; D004492:Edetic Acid; D000251:Adenosine Triphosphatases; C027201:ectoATPase; D008274:Magnesium; D002118:Calcium