The effect of hypo-osmolarity upon transepithelial ion transport in cultured renal epithelial layers (MDCK).
Regulatory volume decrease after exposure to hypo-osmotic media in MDCK epithelial cells results from activation of both K+ and Cl- conductances. Swelling-stimulated 86Rb(K) losses were observed only across the basal-lateral membrane and were relatively insensitive to 10 mM Ba2+. The effect of hypo-osmotic media upon MDCK epithelia mounted in Ussing chambers has been investigated. Exposure of the basal-lateral surfaces to hypo-osmotic media resulted in a transient stimulation of inward short-circuit current (Isc) followed by inhibition of inward Isc in both control layers and in layers where inward current (due to transepithelial Cl- secretion) was first stimulated by 5 microM prostaglandin E1 (PGE1). The transient stimulation of inward current by hypo-osmotic media was not markedly attenuated by 10 mM Ba2+ in PGE1-stimulated layers. After stimulation of inward (Cl(-)-secretory) current to high levels by 10 microM adrenaline, the predominant effect of basal-lateral exposure to hypo-osmotic media was an inhibition of the inward current. This inhibition was partially reversed by 40 microM 4,4'-diisothiocyanatostilbene-2,2'-disulphonate (DIDS). The stimulation, then inhibition, of inward Isc is likely to be the result of separate swelling-induced K+ and Cl- conductances (respectively) at the basal-lateral membrane. The swelling-stimulated Cl- conductance is distinct from the apical Cl- conductance regulated by PGE1 or adrenaline.
Simmons
N L
NL
Department of Physiological Sciences, Medical School, Newcastle upon Tyne, UK.
D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid; D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D000527:Alprostadil / Q000494:pharmacology; D000818:Animals; D001464:Barium / Q000494:pharmacology; D017609:Barium Compounds; D001693:Biological Transport, Active / Q000187:drug effects; D002478:Cells, Cultured; D002712:Chlorides; D004837:Epinephrine / Q000494:pharmacology; D004848:Epithelium / Q000378:metabolism; D007477:Ions; D007668:Kidney / Q000187:drug effects / Q000378:metabolism*; D009994:Osmolar Concentration; D011188:Potassium / Q000378:metabolism; D012413:Rubidium / Q000378:metabolism
D017609:Barium Compounds; D002712:Chlorides; D007477:Ions; C024986:barium chloride; D001464:Barium; D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid; D000527:Alprostadil; D012413:Rubidium; D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid; D011188:Potassium; D004837:Epinephrine