Volume regulation in NIH/3T3 cells not expressing P-glycoprotein. I. Regulatory volume decrease Article uri icon

abstract

  • Exposure of NIH/3T3 fibroblasts not expressing P-glycoprotein to 50, 30, 20, and 10%25 hyposmotic solutions led to cell volume increases of 70, 32, 21, and 12%25, respectively. After swelling, NIH/3T3 cells exhibited regulatory volume decrease (RVD), attaining complete volume recovery after 30 min except in 50%25 hyposmotic solution, in which volume recovery was 76%25. RVD was accelerated by gramicidin and inhibited by the Cl channel blockers 5-nitro-2(3-phenylpropylamino)-benzoic acid, 1,9-dideoxyforskolin, dipyridamole, and niflumic acid and by the K channel blocker quinidine. RVD was reduced 15%25 by removal of extracellular Ca. The pathway opened by hypotonicity was highly permeable to K and Rb and only partly permeable to other cations. Most anions were able to permeate, with a permeability ranking of nitrate > benzoate = iodide > thiocyanate > chloride >> gluconate. The pathway was permeable to neutral amino acids, with a permeability ranking of glycine > alanine > glutamate > taurine > γ- aminobutyric acid > glutamine. The pathway was not permeable to basic amino acids. These results show that, despite the absence of P-glycoprotein, NIH/3T3 cells exhibit RVD with properties similar to those expressed in most cell types.

publication date

  • 1997-01-01