caa a22 4500 469078928 CHVBK 20180323132943.0 cr unu---uuuuu 170328e19920101xx s 000 0 eng 10.1007/BF00175476 doi (NATIONALLICENCE)springer-10.1007/BF00175476 The kinetics of the inhibition by dihydroouabain of the sodium pump current in single rabbit cardiac Purkinje cells [Elektronische Daten] [F. Bielen, H. Glitsch, F. Verdonck] Summary: The kinetics of the inhibition by dihydroouabain (DHO) of the Na pump current were studied in isolated rabbit cardiac Purkinje cells by means of whole-cell recording. A fast exchange of the extracellular solution at the membrane of the cell studied was performed via two multibarrelled pipettes nearby. Judging from the steady-state inhibition of the Na pump current at various DHO concentrations half maximal inhibition occured at 1 × 10−5 mol/l DHO in a medium containing 2 mmol/1 K+ and at 3.5 × 10−5 mol/l DHO in a solution containing 10.8 mmol/1 K+. Assuming a reversible one-to-one binding reaction, the time course of DHO binding and unbinding was analysed under a variety of conditions. It was shown that the antagonistic effect of K+ on the inhibition of the pump current was entirely due to a decrease of the association rate constant of DHO binding to the sodium pump at higher K+ concentrations. The association rate constant amounted to 1 × 104 (mol/l)−1 · s−1 at 2 mmol/1 K+ and to 2.8 × 103 (mol/l)−1 · s−1 at 10.8 mmol/l K+. The dissociation rate constant of DHO unbinding remained unchanged (∼0.06 s−1). The equilibrium dissociation constant KD for the inhibition of the pump current by DHO decreased by a factor 3 to 5 if the Na+ concentration of the patch pipette solution was augmented from 5 to 50 mmol/l. Increasing DHO concentrations inhibited the pump current increasingly faster and to a larger extent. The KD values derived showed little variation with the concentration of DHO applied. It is concluded that the inhibition by DHO of the pump current in cardiac Purkinje cells can be adequately described by an one-to-one binding reaction between the cardioactive steroid and the pump molecules. The reaction is modulated by external K and internal Na ions. Springer-Verlag, 1992 Dihydroouabain nationallicence Sodium pump current nationallicence Kinetics of binding and unbinding nationallicence Cardiac Purkinje cells nationallicence Bielen F. The Interdisciplinary Research Centre, Catholic University of Leuven, Campus Kortrijk, B-8500, Kortrijk, Belgium aut Glitsch H. Department of Cell Physiology, Ruhr-University Bochum, P.O. Box 102148, W-4630, Bochum, Federal Republic of Germany aut Verdonck F. The Interdisciplinary Research Centre, Catholic University of Leuven, Campus Kortrijk, B-8500, Kortrijk, Belgium aut Naunyn-Schmiedeberg's Archives of Pharmacology Springer-Verlag 345/1(1992-01-01), 100-107 0028-1298 345:1<100 1992 345 210 https://doi.org/10.1007/BF00175476 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF00175476 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Bielen F. The Interdisciplinary Research Centre, Catholic University of Leuven, Campus Kortrijk, B-8500, Kortrijk, Belgium aut NATIONALLICENCE 700 1- Glitsch H. Department of Cell Physiology, Ruhr-University Bochum, P.O. Box 102148, W-4630, Bochum, Federal Republic of Germany aut NATIONALLICENCE 700 1- Verdonck F. The Interdisciplinary Research Centre, Catholic University of Leuven, Campus Kortrijk, B-8500, Kortrijk, Belgium aut NATIONALLICENCE 773 0- Naunyn-Schmiedeberg's Archives of Pharmacology Springer-Verlag 345/1(1992-01-01), 100-107 0028-1298 345:1<100 1992 345 210 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer