Dual effects of ATP on the potassium channel and intracellular Ca2+ release in smooth muscle cells of the bovine brain arteries.
ATP produced whole-cell potassium currents with a latency of 200 msec in cultured smooth muscle cells of bovine brain arteries. The currents were evoked via an ATP receptor linked to a pertussis toxin-insensitive G-protein, which is not involved in phospholipase C (PLC)-mediated signal transduction, and were not regulated by protein kinase A or C. In the cell-attached patches, ATP elicited single channel currents with two major classes of slope conductances and these currents were again induced within 100 msec after bath-application of ATP outside the patch pipette. In addition, ATP enhanced intracellular free Ca2+ concentration ([Ca2+]i) with no initiation time in the presence and absence of extracellular Ca2+, and this enhancement was not blocked by a PLC inhibitor. These results, thus, suggest that the activation of the potassium channel and the enhancement of [Ca2+]i induced by ATP may be caused by a direct action of the G-protein beta gamma subunits.
D000255:Adenosine Triphosphate / Q000494:pharmacology*; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002417:Cattle; D002478:Cells, Cultured; D002536:Cerebral Arteries / Q000187:drug effects / Q000502:physiology*; D002540:Cerebral Cortex / Q000098:blood supply; D005071:Evoked Potentials / Q000187:drug effects*; D019204:GTP-Binding Proteins / Q000502:physiology*; D006153:Guanosine Diphosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D007424:Intracellular Fluid / Q000378:metabolism; D007700:Kinetics; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000502:physiology*; D018408:Patch-Clamp Techniques; D037342:Pertussis Toxin; D015221:Potassium Channels / Q000187:drug effects / Q000502:physiology*; D018048:Receptors, Purinergic P2 / Q000187:drug effects / Q000502:physiology*; D015398:Signal Transduction; D013873:Thionucleotides / Q000494:pharmacology; D010738:Type C Phospholipases / Q000378:metabolism; D010566:Virulence Factors, Bordetella / Q000494:pharmacology*
D015221:Potassium Channels; D018048:Receptors, Purinergic P2; D013873:Thionucleotides; D010566:Virulence Factors, Bordetella; D006153:Guanosine Diphosphate; C023427:guanosine 5'-O-(2-thiodiphosphate); D000255:Adenosine Triphosphate; D037342:Pertussis Toxin; D010738:Type C Phospholipases; D019204:GTP-Binding Proteins; D002118:Calcium