title: Effects of bradykinin on cell volume and intracellular pH in NIH 3T3 fibroblasts expressing the ras oncogene.
abstract: BCECF fluorescence has been applied to determine intracellular pH (pHi) in NIH 3T3 fibroblasts expressing the Ha-ras oncogene (+ras) and otherwise identical cells not expressing the oncogene (-ras). In +ras cells, pHi is significantly more alkaline (6.79 +/- 0.03 n = 12) than in -ras cells (6.64 +/- 0.02, n = 8). Bradykinin (100 nmol/l) leads to intracellular alkalinization in both +ras (to 6.96 +/- 0.04, n = 12) and -ras cells (to 6.85 +/- 0.02, n = 8). The effect of bradykinin is completely abolished in the presence of dimethylamiloride (100 mumol/l), which does not modify pHi in the absence of bradykinin. Similar to bradykinin, cell shrinkage by addition of 15 mmol/l NaCl to the extracellular fluid leads to intracellular alkalinization (by 0.08 +/- 0.01, n = 15). Cell volume is significantly greater in +ras cells (2.7 +/- 0.4 pl, n = 15) than in -ras cells (2.2 +/- 0.4 pl, n = 15). Bradykinin leads to cell shrinkage in both +ras cells (by 7 +/- 1%, n = 17) and -ras cells (by 5 +/- 1%, n = 15). The effect of bradykinin on cell volume can be reversed by the reduction of extracellular NaCl concentration by 15 mmol/l NaCl in +ras cells and by 7 mmol/l NaCl in -ras cells. This maneuver completely abolishes (in -ras cells) or blunts (in +ras cells) the alkalinizing effect of bradykinin. In conclusion, +ras cells are more alkaline than -ras cells. Bradykinin leads to further intracellular alkalinization by activation of the Na+/H(+)-exchanger, at least in part secondary to hormone-induced cell shrinkage.
authors.affiliation: Institut für Physiologie, Universität Innsbruck, Austria.
authors.forename: M
authors.initials: M
authors.lastname: Ritter
authors.forename: E
authors.initials: E
authors.lastname: Wöll
authors.forename: D
authors.initials: D
authors.lastname: Häussinger
authors.forename: F
authors.initials: F
authors.lastname: Lang
mesh_terms: D016475:3T3 Cells; D000584:Amiloride / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D001920:Bradykinin / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D002352:Carrier Proteins / Q000378:metabolism; D005452:Fluoresceins; D015870:Gene Expression; D011905:Genes, ras / Q000502:physiology; D006863:Hydrogen-Ion Concentration; D015640:Ion Channel Gating; D051379:Mice; D015221:Potassium Channels / Q000502:physiology; D017923:Sodium-Hydrogen Exchangers; D014162:Transfection
chemical_list: D002352:Carrier Proteins; D005452:Fluoresceins; D015221:Potassium Channels; D017923:Sodium-Hydrogen Exchangers; C039465:5-dimethylamiloride; D000584:Amiloride; C043829:2',7'-bis(carboxyethyl)-5(6)-carboxyfluorescein; D001920:Bradykinin