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Title: Regulation of Na+-H+ exchange in normal NIH-3T3 cells and in NIH-3T3 cells expressing the ras oncogene

Our laboratory and others have demonstrated that Na+-H+ exchange can be regulated by two different pathways; one that is mediated by an inositol trisphosphate-stimulated increase in intracellular calcium activity, and one that is mediated by an increase in protein kinase C activity. To determine whether one of these pathways is more important than the other, or whether one pathway is physiologically relevant, we employed normal NIH-3T3 cells (3T3 cells) and NIH-3T3 cells expressing the EJ human bladder ras oncogene (EJ cells). The EJ cells were chosen because they provide a genetic model that does not exhibit serum- or platelet-derived growth factor (PDGF)-stimulated inositol trisphosphate release or Ca2+ mobilization. It was found that serum- or PDGF-stimulated Na+-H+ exchange was more pronounced in EJ cells than in control 3T3 cells. As expected, serum- or PDGF-stimulated Na+-H+ exchange in 3T3 cells was inhibited by chelating intracellular Ca2+ with the intracellular Ca2+ chelator quin2, by the intracellular Ca2+ antagonist 8-(N,N-diethylamino)octyl 3,4,5-trimethoxybenzoate (TMB-8), and by the calmodulin antagonist trifluoperazine. In contrast, these agents did not inhibit serum- or PDGF-stimulated Na+-H+ exchange in EJ cells. Activators of protein kinase C (e.g., 1-oleoyl-2-acetylglycerol or biologically active phorbol esters) were found to stimulate Na+-H+ exchange in EJ cellsmore » to the same extent as serum. However, these agents were considerably less effective than serum in control 3T3 cells. Despite these findings, PDGF did not stimulate diacylglycerol levels in EJ cells.« less
Authors:
; ; ; ;
Publication Date:
OSTI Identifier:
5985690
Resource Type:
Journal Article
Resource Relation:
Journal Name: Am. J. Physiol.; (United States); Journal Volume: 256
Research Org:
Univ. of Health Sciences, Chicago Medical School, IL (USA)
Country of Publication:
United States
Language:
English
Subject:
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.; BLOOD COAGULATION FACTORS; BIOCHEMICAL REACTION KINETICS; FIBROBLASTS; ION EXCHANGE; PHORBOL ESTERS; BIOLOGICAL EFFECTS; BIOLOGICAL PATHWAYS; BLADDER; BLOOD; CALCIUM COMPOUNDS; CALMODULIN; ENZYME ACTIVITY; GENE REGULATION; GENES; HYDROGEN IONS; MEMBRANE TRANSPORT; MICE; PHOSPHOLIPIDS; PHOSPHOTRANSFERASES; SODIUM COMPOUNDS; ALKALI METAL COMPOUNDS; ALKALINE EARTH METAL COMPOUNDS; ANIMAL CELLS; ANIMALS; BIOLOGICAL MATERIALS; BODY; BODY FLUIDS; CARCINOGENS; CHARGED PARTICLES; COAGULANTS; CONNECTIVE TISSUE CELLS; DRUGS; ENZYMES; ESTERS; HEMATOLOGIC AGENTS; IONS; KINETICS; LIPIDS; MAMMALS; MATERIALS; ORGANIC COMPOUNDS; ORGANIC PHOSPHORUS COMPOUNDS; ORGANS; PHOSPHORUS-GROUP TRANSFERASES; PROTEINS; REACTION KINETICS; RODENTS; SOMATIC CELLS; TRANSFERASES; URINARY TRACT; VERTEBRATES 560300* -- Chemicals Metabolism & Toxicology