title: Polarized 86Rb+ effluxes in primary cultures of rabbit kidney proximal cells: role of calcium and hypotonicity.
abstract: Isolated proximal cells from rabbit kidney were seeded on collagen-coated permeable supports. After 8 days, the cultured cells became organized as a confluent monolayer. The proximal origin of the monolayer was confirmed by enzymatic, immunological, electrical and electron microscopical studies. The epithelia exhibited a morphological polarity that allowed for measurements of effluxes across the apical or the basolateral membranes. 86Rb was used as an isotopic tracer to indicate potassium movements. The 86Rb+ efflux across the basolateral face was 1.93-times that across the apical face, and both effluxes were pH dependent. Apical and basolateral 86Rb+ effluxes increased when the Ca2+ ionophore ionomycin (3 microM) was applied and when monolayers were exposed to a hypotonic medium. A pharmacological study revealed that BaCl2 (5 mM), tetraethylammonium (TEA, 20 mM) and Leiurus quinquestriatus hebraeus scorpion venom (from which charybdotoxin is extracted) abolished both ionomycin and hypotonically-stimulated effluxes, whereas apamin had no significant effect on the hypotonically-stimulated 86Rb+ efflux. This stimulated efflux was also abolished when monolayers were preincubated with pertussis toxin, but did not decrease in a Ca2(+)-free medium.
authors.affiliation: Département de Biologie, CEN Saclay, Gif-sur-Yvette, France.
authors.forename: S
authors.initials: S
authors.lastname: le Maout
authors.forename: M
authors.initials: M
authors.lastname: Tauc
authors.forename: N
authors.initials: N
authors.lastname: Koechlin
authors.forename: P
authors.initials: P
authors.lastname: Poujeol
mesh_terms: D000818:Animals; D001030:Apamin / Q000494:pharmacology; D001464:Barium / Q000494:pharmacology; D017609:Barium Compounds; D002118:Calcium / Q000502:physiology*; D002462:Cell Membrane / Q000378:metabolism; D002463:Cell Membrane Permeability; D002478:Cells, Cultured; D002712:Chlorides; D000242:Cyclic AMP / Q000096:biosynthesis; D005455:Fluorescent Antibody Technique; D006863:Hydrogen-Ion Concentration; D007038:Hypotonic Solutions; D015759:Ionomycin / Q000494:pharmacology; D007687:Kidney Tubules, Proximal / Q000378:metabolism*; D008297:Male; D008854:Microscopy, Electron; D037342:Pertussis Toxin; D011188:Potassium / Q000378:metabolism*; D011817:Rabbits; D012414:Rubidium Radioisotopes; D019789:Tetraethylammonium; D013757:Tetraethylammonium Compounds / Q000494:pharmacology; D010566:Virulence Factors, Bordetella / Q000494:pharmacology
chemical_list: D017609:Barium Compounds; D002712:Chlorides; D007038:Hypotonic Solutions; D012414:Rubidium Radioisotopes; D013757:Tetraethylammonium Compounds; D010566:Virulence Factors, Bordetella; C024986:barium chloride; D001030:Apamin; D001464:Barium; D015759:Ionomycin; D019789:Tetraethylammonium; D000242:Cyclic AMP; D037342:Pertussis Toxin; D011188:Potassium; D002118:Calcium