caa a22 4500 465826334 CHVBK 20180323112150.0 cr unu---uuuuu 170327e19900401xx s 000 0 eng 10.1007/BF00258767 doi (NATIONALLICENCE)springer-10.1007/BF00258767 Characteristics of ouabain binding to isolated trout hepatocytes [Elektronische Daten] [Laurence Bianchini, Barthélémy Fossat, Jacqueline Porthé-Nibelle, Brahim Lahlou] Summary: Na+, K+ exchanges were studied in isolated hepatocytes of the rainbow trout, Salmo gairdneri. Ouabain at 10−4 M produced maximal inhibition (95%) of K+ uptake and enhanced intracellular Na+ accumulation, showing that active fluxes account for a very large proportion of Na+ and K+ exchanges. Inhibition of the Na−K pump by ouabain was significant at low concentrations (10−8 M). When external K+ concentration was reduced from 7 mM to 0.5 mM, half maximum inhibition (IC50) of K+ uptake was obtained at a 22-fold lower concentration of ouabain confirming that ouabain and potassium compete at the same pump site. Time-course analysis of [3H]ouabain binding indicated a two-component kinetics: one component saturable and dependent on K+ concentration in the medium, the other linear and independent of external K+. The ouabain binding site number, determined by Scatchard plots, remained constant (ca. 2.5·105 per cell) and independent of the external K+ concentration (7, 0.5 or 0 mM), while the dissociation constant (KD) decreased from 4.2 μM to 7.3 nM when K+ was removed from the Hank's medium. These ouabain binding sites are characterized by an exceptionally low turnover rate (400 min−1), as estimated from ouabain-sensitive K+ flux, in comparison to those described in other cell types of higher vertebrates. At each external K+ concentration studied, the inhibition of K+ uptake and ouabain binding measured as a function of ouabain concentration indicated a strict correlation between the degree of K pump inhibition and the amount of bound glycoside. Springer-Verlag, 1990 Cation fluxes nationallicence Trout ( Salmo gaidneri ) nationallicence Hepatocytes nationallicence Ouabain binding kinetics nationallicence Ouabain sites number nationallicence Bianchini Laurence Laboratoire de Physiologie Cellulaire et Comparée, Faculté des Sciences, Université de Nice-Sophia Antipolis, Parc Valrose, 06034, Nice Cedex, France aut Fossat Barthélémy Laboratoire de Physiologie Cellulaire et Comparée, Faculté des Sciences, Université de Nice-Sophia Antipolis, Parc Valrose, 06034, Nice Cedex, France aut Porthé-Nibelle Jacqueline Laboratoire de Physiologie Cellulaire et Comparée, Faculté des Sciences, Université de Nice-Sophia Antipolis, Parc Valrose, 06034, Nice Cedex, France aut Lahlou Brahim Laboratoire de Physiologie Cellulaire et Comparée, Faculté des Sciences, Université de Nice-Sophia Antipolis, Parc Valrose, 06034, Nice Cedex, France aut Journal of Comparative Physiology B Springer-Verlag 160/1(1990-04-01), 93-98 0174-1578 160:1<93 1990 160 360 https://doi.org/10.1007/BF00258767 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF00258767 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Bianchini Laurence Laboratoire de Physiologie Cellulaire et Comparée, Faculté des Sciences, Université de Nice-Sophia Antipolis, Parc Valrose, 06034, Nice Cedex, France aut NATIONALLICENCE 700 1- Fossat Barthélémy Laboratoire de Physiologie Cellulaire et Comparée, Faculté des Sciences, Université de Nice-Sophia Antipolis, Parc Valrose, 06034, Nice Cedex, France aut NATIONALLICENCE 700 1- Porthé-Nibelle Jacqueline Laboratoire de Physiologie Cellulaire et Comparée, Faculté des Sciences, Université de Nice-Sophia Antipolis, Parc Valrose, 06034, Nice Cedex, France aut NATIONALLICENCE 700 1- Lahlou Brahim Laboratoire de Physiologie Cellulaire et Comparée, Faculté des Sciences, Université de Nice-Sophia Antipolis, Parc Valrose, 06034, Nice Cedex, France aut NATIONALLICENCE 773 0- Journal of Comparative Physiology B Springer-Verlag 160/1(1990-04-01), 93-98 0174-1578 160:1<93 1990 160 360 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer