title: Demonstration of a direct effect of atrial natriuretic factor on epithelium: study in cultured pig kidney cells.
abstract: Cultured renal tubular cells represent a convenient model to assess a possibility of a direct effect of atrial natriuretic factor (ANF) on renal epithelial cells independent of hemodynamic influences. LLC-PK1 cells were grown to confluence on collagen-coated polycarbonate membranes. Studies were performed in modified Ussing chambers with a symmetrical composition of bathing solutions. LLC-PK1 monolayers expressed polarity with transepithelial potential differences (PD) 0.54 +/- 0.31 mV, short-circuit current (SCC) 1.85 +/- 0.49 microA cm-2, and transepithelial resistance 308 +/- 79 omega cm2. ANF caused a decrease in PD and SCC. The effect of ANF was abolished by eliminating Na+ from the bathing solution. Dibutyryl cyclic GMP (db-c-GMP) and Na+ nitroprusside mimicked the effect of ANF, which had no additive effect following pretreatment with these compounds. Cyclic AMP (c-AMP) reversed the effect of ANF. 22Na+ unidirectional flux was significantly inhibited by ANF. In summary, in cultured renal tubular cells ANF decreases SCC and PD, and decreases Na+ influx, suggesting a direct effect on epithelial ion transport.
mesh_terms: D000818:Animals; D009320:Atrial Natriuretic Factor / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D002478:Cells, Cultured; D004848:Epithelium / Q000187:drug effects; D007684:Kidney Tubules / Q000187:drug effects* / Q000378:metabolism; D008564:Membrane Potentials / Q000187:drug effects; D009599:Nitroprusside / Q000494:pharmacology; D012265:Ribonucleotides / Q000494:pharmacology; D012964:Sodium / Q000378:metabolism
chemical_list: D012265:Ribonucleotides; D009599:Nitroprusside; D009320:Atrial Natriuretic Factor; D012964:Sodium