A role for a pertussis toxin-sensitive trimeric G-protein in store-operated Ca2+ inflow in hepatocytes.
The mechanism of store-operated Ca2+ inflow in hepatocytes was investigated using fluo-3 and fura-2 to monitor changes in the concentration of intracellular free Ca2+ in single cells, and 1-(alpha-glycerophosphoryl)-myo-inositol 4,5-diphosphate, P4(5)-1-(2-nitrophenyl)ethyl ester ('caged' GPIP2) and 'caged' guanosine 5'-[gamma thio]triphosphate (GTP gamma S) (introduced into the cytoplasmic space by microinjection), thapsigargin and 2,5-di-tert- butylhydroquinone (DBHQ) to stimulate Ca2+ inflow. Photolysis of 'caged' GPIP2 or 'caged' GTP gamma S stimulated Ca2+ inflow. The abilities of GPIP2, thapsigargin and DBHQ to stimulate Ca2+ inflow were inhibited by the pre-treatment of hepatocytes with pertussis toxin in vivo for 36 h. Thapsigargin-stimulated Ca2+ inflow was also inhibited by guanosine 5'-[beta-thio]diphosphate (GDP beta S) (introduced by microinjection). It is concluded that, in hepatocytes, store-operated Ca2+ inflow induced by the actions of either inositol 1,4,5-trisphosphate, thapsigargin or DBHQ requires a pertussis toxin-sensitive trimeric G-protein.
Department of Medical Biochemistry, School of Medicine, Flinders University, Adelaide, Australia.
L A
LA
Berven
G J
GJ
Barritt
D000814:Aniline Compounds; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D005456:Fluorescent Dyes; D016257:Fura-2; D019204:GTP-Binding Proteins / Q000502:physiology*; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000494:pharmacology; D006153:Guanosine Diphosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D006873:Hydroquinones / Q000494:pharmacology; D007295:Inositol Phosphates; D008099:Liver / Q000187:drug effects / Q000378:metabolism*; D046911:Macromolecular Substances; D037342:Pertussis Toxin; D018129:Phosphatidylinositol Phosphates / Q000494:pharmacology; D010782:Photolysis; D051381:Rats; D013729:Terpenes / Q000494:pharmacology; D019284:Thapsigargin; D013873:Thionucleotides / Q000494:pharmacology; D010566:Virulence Factors, Bordetella / Q000494:pharmacology*; D014966:Xanthenes
C087840:1-(glycerophosphoryl)-myo-inositol 4,5-diphosphate P(4(5))-1-(2-nitrophenyl)ethyl ester; D000814:Aniline Compounds; D005456:Fluorescent Dyes; D006873:Hydroquinones; D007295:Inositol Phosphates; D046911:Macromolecular Substances; D018129:Phosphatidylinositol Phosphates; D013729:Terpenes; D013873:Thionucleotides; D010566:Virulence Factors, Bordetella; D014966:Xanthenes; D006153:Guanosine Diphosphate; C059715:Fluo-3; C019359:2,5-di-tert-butylhydroquinone; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D019284:Thapsigargin; C023427:guanosine 5'-O-(2-thiodiphosphate); D037342:Pertussis Toxin; D019204:GTP-Binding Proteins; D002118:Calcium; D016257:Fura-2