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Sodium load and high affinity ouabain binding in rat and guinea‐pig cardiac tissue
Author(s) -
Herzig Stefan,
Mohr Klaus
Publication year - 1985
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/j.1476-5381.1985.tb16150.x
Subject(s) - ouabain , monensin , binding site , sodium , ionophore , chemistry , guinea pig , dibucaine , biophysics , biochemistry , endocrinology , biology , membrane , organic chemistry
1 An estimation of the actual Na/K‐ATPase transport activity in intact cardiac cells was made by measuring the binding of [ 3 H]‐ouabain to rat and guinea‐pig ventricular strips. At the low [ 3 H]‐ouabain concentration of 1 n m equilibrium binding was hardly obtained after an incubation time of five hours. 2 Different procedures known to alter the sodium load of the cardiac preparations influenced [ 3 H]‐ouabain binding: the sodium ionophore monensin enhanced [ 3 H]‐ouabain binding, the local anaesthetic dibucaine and a reduction of external sodium ion concentration diminished [ 3 H]‐ouabain binding; [ 3 H]‐ouabain binding was similarly affected by these procedures in the rat and guinea‐pig. 3 Since [ 3 H]‐ouabain binding occurred predominantly at the high‐affinity binding sites of rat myocardium under the applied experimental conditions, it was concluded that these binding sites represent Na/K‐ATPase molecules involved in sodium ion transport.