Regulation of the serum-activated Ca(2+)-dependent chloride channel in Xenopus oocytes.
Fetal bovine serum evoked Ca(2+)-dependent chloride currents with two components in Xenopus oocytes. The evoked currents were inhibited by GDP beta S, but not by pertussis toxin (PTX). An inositol 1,4,5-triphosphate (IP3) receptor antagonist, heparin completely inhibited the currents, although a phospholipase C inhibitor, neomycin had no effect. The serum-activated currents were enhanced to 171% by a selective protein kinase C (PKC) inhibitor, GF109203X. By contrast, a potent PKC activator, TPA, abolished the initial component of the currents and arachidonic acid enhanced this effect. The effects of TPA and/or arachidonic acid on the currents inhibited by GF109203X. These results indicate that the receptor for serum is linked to a PTX-insensitive G-protein involving cytosolic Ca2+ release through IP3 and PKC activation by a mechanism independent of a phospholipase C-mediated phospholipid signaling. Furthermore, the evoked currents are regulated by PKC and arachidonic acid appears to potentiate its effect.
Matsuoka
T
T
Department of Public Health, Kobe University School of Medicine, Japan.
Nishizaki
T
T
Ikeuchi
Y
Y
D000818:Animals; D016718:Arachidonic Acid / Q000502:physiology; D001769:Blood; D002118:Calcium / Q000502:physiology*; D015220:Calcium Channels / Q000502:physiology; D002417:Cattle; D018118:Chloride Channels / Q000502:physiology*; D002712:Chlorides / Q000502:physiology*; D005260:Female; D053496:Inositol 1,4,5-Trisphosphate Receptors; D015640:Ion Channel Gating; D009865:Oocytes; D011493:Protein Kinase C / Q000502:physiology; D018160:Receptors, Cytoplasmic and Nuclear / Q000502:physiology; D015398:Signal Transduction; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D010738:Type C Phospholipases / Q000502:physiology; D014982:Xenopus laevis
D015220:Calcium Channels; D018118:Chloride Channels; D002712:Chlorides; D053496:Inositol 1,4,5-Trisphosphate Receptors; D018160:Receptors, Cytoplasmic and Nuclear; D016718:Arachidonic Acid; D011493:Protein Kinase C; D010738:Type C Phospholipases; D013755:Tetradecanoylphorbol Acetate; D002118:Calcium