VOLUME REGULATION IN HUMAN FIBROBLASTS - ROLE OF CA2-LIPOXYGENASE PRODUCTS IN THE ACTIVATION OF THE CL- EFFLUX( AND 5)

Trypsinized human skin fibroblasts in suspension perform regulatory vo lume decrease (RVD) after cell swelling in hypotonic medium. During RV D, Cl-36- efflux is dramatically increased and the cell membrane is de polarized, indicating the activation of Cl- channels. This activation of Cl- channels depends on extracellular as well as on intracellular C a2+. The swelling-induced Cl- efflux and the RVD response are inhibite d by the 5-lipoxygenase inhibitor ETH 615-139. Finally, following hypo tonic treatment, cellular pH decreases. The pH decrease does not invol ve the Cl-/HCO3- exchange because it is independent of the external Cl - concentration.