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The uptake of cardiac glycosides in relation to their actions in isolated cardiac muscle
Author(s) -
GODFRAIND T.,
LESNE M.
Publication year - 1972
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.1476-5381.1972.tb08146.x
Subject(s) - digitoxin , ouabain , cardiac glycoside , chemistry , inotrope , digitalis , glycoside , digoxin , sodium , sodium pump , cardiac muscle , pharmacology , medicine , stereochemistry , biology , heart failure , organic chemistry
Summary1 The uptake of 3 H‐digitoxin, 3 H‐ouabain and 3 H‐dihydro‐ouabain by isolated guinea‐pig atria has been studied and compared with the inhibition of the sodium pump and with the inotropic effect. 2 Analysis of the curve relating the uptake of digitoxin and ouabain at equilibrium to the bath concentration enabled a non‐saturable and a saturable binding site to be distinguished. 3 The uptake of inactive doses of dihydro‐ouabain was only by a non‐saturable mechanism. 4 The uptake of labelled digitoxin and ouabain was reduced in the presence of another glycoside. The amount of bound glycoside was nearly equivalent to the estimated non‐saturable uptake. 5 The uptake was reduced at 4° C to the clearance of the non‐saturable site. 6 ED50 of digitoxin and of ouabain for inhibition of the sodium pump were measured and compared to the ED50 for inotropic effect and to the concentrations producing a half‐saturation of the saturable binding site. 7 It is concluded that binding to the saturable site may be responsible for the cardiac actions of the glycosides.