Abstract
P-glycoprotein-associated Cl- conductance is activated by cell swelling; the ensuing Cl- efflux is thought to contribute to cell volume regulation. We tested this hypothesis in human breast cancer cells transfected with human mdr1 complementary DNA, which display P-glycoprotein-associated, swelling-activated Cl- currents. The Cl- electrochemical driving force favors Cl- efflux, but there was no appreciable Cl- loss or regulatory volume decrease (both assessed with fluorescent dyes) during the exposure to hyposmotic solution. Calculations indicate that the swelling-activated Cl- current is insufficient to cause a significant Cl- efflux. Hence, regulatory volume decrease is not a function of P-glycoprotein.
Footnotes
-
↵1 This work was supported in part by a grant from the John Sealy Memorial Endowment Fund. Mr. C. G. Vanoye was supported by NIH Grant DK08865.
-
↵3 To whom reprint requests should be addressed, at: Department of Physiology and Biophysics, The University of Texas Medical Branch, Basic Science Bldg., Galveston, TX 77555-0641.
- Received October 1, 1993.
- Accepted December 16, 1993.
- ©1994 American Association for Cancer Research.
Volume 54, Issue 3
