ATP produces potassium currents via P3 purinoceptor in the follicle cell layer of Xenopus oocytes.
Purinoceptor agonists produced potassium currents with the order of potency: ATP > adenosine = ADP = AMP > beta,gamma-methylene ATP, while a small response or no response was induced by 2-methylthio ATP, UTP, or alpha,beta-methylene ATP. The response induced by beta,gamma-methylene ATP was completely inhibited in the presence of alpha,beta-methylene ATP, suggesting that the relevant receptor for these agonists was a P3 purinoceptor. ATP induced currents with a latency of 24 s and the currents were not induced in defolliculated oocytes. The currents were not affected by either the Gi/o-protein inhibitor, pertussis toxin (PTX), or the selective cAMP-dependent protein kinase inhibitor, H-89, or the phospholipase C (PLC) inhibitor, neomycin, or the phospholipase A2 (PLA2) inhibitor, 4-bromophenacyl bromide. The currents were enhanced by the selective protein kinase C (PKC) inhibitor, GF109203X, but otherwise, they were reduced by the potent PKC activator, 12-O-tetradecanoylphorbol-13-acetate. The results of the present study suggest that a P3 purinoceptor in the follicle cell layer of oocytes is involved in activation of potassium channels and that the evoked currents are regulated by PLC/PLA2-independent PKC activation.
Matsuoka
T
T
Department of Physiology, Kobe University School of Medicine, Japan.
Nishizaki
T
T
Nomura
T
T
Mori
M
M
Okada
Y
Y
D000255:Adenosine Triphosphate / Q000494:pharmacology*; D000818:Animals; D005260:Female; D019204:GTP-Binding Proteins / Q000378:metabolism; D008564:Membrane Potentials / Q000187:drug effects; D009865:Oocytes / Q000166:cytology / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism; D018408:Patch-Clamp Techniques; D037342:Pertussis Toxin; D010741:Phospholipases A / Q000378:metabolism; D054467:Phospholipases A2; D015221:Potassium Channels / Q000187:drug effects* / Q000502:physiology; D011493:Protein Kinase C / Q000378:metabolism; D011983:Receptors, Purinergic / Q000502:physiology*; D010738:Type C Phospholipases / Q000378:metabolism; D010566:Virulence Factors, Bordetella / Q000494:pharmacology; D014981:Xenopus
D015221:Potassium Channels; D011983:Receptors, Purinergic; D010566:Virulence Factors, Bordetella; D000255:Adenosine Triphosphate; D037342:Pertussis Toxin; D011493:Protein Kinase C; D010741:Phospholipases A; D054467:Phospholipases A2; D010738:Type C Phospholipases; D019204:GTP-Binding Proteins