Loss of bradykinin receptors and TPA-stimulated Na+ influx in SV40-transformed WI-38 cells.
Mitogenic stimulation of Na(+)-H+ exchange activity, as defined by the level of 5-(N,N-hexamethylene)amiloride (HMA)-sensitive Na+ influx, was compared in WI-38 and SV40 virus-transformed WI-38 fibroblasts. Serum or bradykinin dramatically stimulated HMA-sensitive Na+ influx in WI-38 cells, whereas in SV40-transformed WI-38 cells, serum, but not bradykinin, produced a large increase in HMA-sensitive Na+ influx. This lack of a bradykinin response was traced to a dramatic reduction in the number of bradykinin receptors, from 470 fmol/mg protein in WI-38 cells to 29 fmol/mg protein in the SV40-transformed WI-38 cells. Transformation of WI-38 cells with SV40 virus also altered the mechanism by which HMA-sensitive Na+ influx is stimulated. In WI-38 cells, 12-O-tetradecanoylphorbol 13-acetate (TPA) dramatically stimulated HMA-sensitive Na+ influx. In SV40-transformed WI-38 cells, TPA alone had no effect on HMA-sensitive influx and inhibited serum-stimulated HMA-sensitive Na+ influx. Down-regulation of protein kinase C activity decreased serum- and TPA-stimulated HMA-sensitive Na+ influx in the WI-38 cells and relieved the TPA inhibition of serum-stimulated HMA-sensitive Na+ influx in the SV40-transformed WI-38 cells.
Etscheid
B G
BG
Department of Pharmacological and Physiological Sciences, University of Chicago, Illinois 60637.
Jamieson
G A
GA
Toscas
K
K
Villereal
M L
ML
D000584:Amiloride / Q000031:analogs & derivatives / Q000494:pharmacology; D001920:Bradykinin / Q000378:metabolism / Q000494:pharmacology*; D002455:Cell Division / Q000187:drug effects; D002460:Cell Line; D002471:Cell Transformation, Neoplastic; D006133:Growth Substances / Q000494:pharmacology; D006801:Humans; D007295:Inositol Phosphates / Q000378:metabolism; D007700:Kinetics; D018002:Receptors, Bradykinin; D017981:Receptors, Neurotransmitter / Q000378:metabolism*; D013539:Simian virus 40 / Q000235:genetics*; D012964:Sodium / Q000378:metabolism*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*
D006133:Growth Substances; D007295:Inositol Phosphates; D018002:Receptors, Bradykinin; D017981:Receptors, Neurotransmitter; C057360:5-(N,N-hexamethylene)amiloride; D000584:Amiloride; D012964:Sodium; D013755:Tetradecanoylphorbol Acetate; D001920:Bradykinin