Inotropic effects of ouabain and Na, K-ATPase activity in failing rabbit hearts.
Left ventricular (LV) function and Na+, K(+)-ATPase activity were studied in rabbit failing heart (FH) obtained by a double pressure plus volume overload which increased LV/body weight ratio by 58%. Ouabain (10(-6) M) increased peak dP/dt by 69% in control hearts (CH) but not in FH. Na+, K(+)-ATPase activity was similar in FH and in CH but the affinity of Na+, K(+)-ATPase for ouabain was significantly higher in CH than in FH (IC50: 2 microM vs 90 microM). The blunted LV contractile response to ouabain in FH is attributed to a decreased Na+, K(+)-ATPase affinity to ouabain and not to a decreased receptor density.
Ezzaher
A
A
INSERM U.400, Faculté de médecine, Créteil, France.
Mougenot
R
R
Baggioni
A
A
el Ouazzani
T
T
Crozatier
B
B
Maixent
J M
JM
D000818:Animals; D002316:Cardiotonic Agents; D006333:Heart Failure / Q000201:enzymology* / Q000503:physiopathology*; D010042:Ouabain / Q000494:pharmacology*; D011817:Rabbits; D000254:Sodium-Potassium-Exchanging ATPase / Q000187:drug effects / Q000378:metabolism*; D016277:Ventricular Function, Left
D002316:Cardiotonic Agents; D010042:Ouabain; D000254:Sodium-Potassium-Exchanging ATPase