title: Loop-diuretic inhibition of adrenaline-stimulated Cl- secretion in a cultured epithelium of renal origin (MDCK).
abstract: Loop diuretics (furosemide, bumetanide, piretanide) inhibit the adrenaline-stimulated short-circuit current due to transepithelial Cl- secretion in cultured renal epithelial layers (MDCK). The inhibition of Cl- secretion by loop diuretics is consistent with the presence of basal-lateral 'cotransport' since inhibition is observed only with the basal applications of loop diuretics, is of high potency (half-maximal bumetanide inhibition being observed at 0.8 microM, bumetanide being more potent than furosemide) and is without effect upon the adrenaline-stimulated increase in tissue conductance. Loop diuretics are also shown to inhibit a component of K+ efflux across the basal-lateral surfaces. Cellular uptake of [3H]bumetanide across both apical and basal surfaces of intact epithelial layers was measured in order to localize the cotransport system. A component of cellular [3H]bumetanide uptake sensitive to competition by 0.1 mM unlabelled loop diuretic is only observed from the basal-lateral cell surfaces. There is no evidence for transepithelial bumetanide secretion as is seen in renal cortex.
mesh_terms: D000818:Animals; D002034:Bumetanide / Q000378:metabolism / Q000494:pharmacology*; D002460:Cell Line; D002712:Chlorides / Q000037:antagonists & inhibitors* / Q000378:metabolism; D004232:Diuretics / Q000494:pharmacology*; D004285:Dogs; D004594:Electrophysiology; D004837:Epinephrine / Q000494:pharmacology*; D004848:Epithelium / Q000378:metabolism; D005665:Furosemide / Q000494:pharmacology*; D007668:Kidney / Q000166:cytology / Q000187:drug effects / Q000378:metabolism* / Q000502:physiology; D011188:Potassium / Q000378:metabolism; D011868:Radioisotopes; D012413:Rubidium / Q000378:metabolism; D013268:Stimulation, Chemical; D013449:Sulfonamides / Q000494:pharmacology*
chemical_list: D002712:Chlorides; D004232:Diuretics; D011868:Radioisotopes; D013449:Sulfonamides; D002034:Bumetanide; D005665:Furosemide; C015451:piretanide; D012413:Rubidium; D011188:Potassium; D004837:Epinephrine