PT  - JOURNAL ARTICLE
AU  - Richard S. Tuttle
AU  - Peter N. Witt
AU  - Alfred Farah
TI  - THERAPEUTIC AND TOXIC EFFECTS OF OUABAIN ON K<sup>+</sup> FLUXES IN RABBIT ATRIA
DP  - 1962 Jul 01
TA  - Journal of Pharmacology and Experimental Therapeutics
PG  - 24--30
VI  - 137
IP  - 1
4099  - http://jpet.aspetjournals.org/content/137/1/24.short
4100  - http://jpet.aspetjournals.org/content/137/1/24.full
SO  - J Pharmacol Exp Ther1962 Jul 01; 137
AB  - Previous experiments with stimulated rabbit atria have indicated that "therapeutic" positive inotropic concentrations of ouabain maintain intracellular K+in vitro and produce no change in vivo. "Toxic" negative inotropic concentrations on the other hand decrease intracellular K+ concentration. Neither the toxic nor therapeutic effects on K+ as determined by terminal analysis of the tissue could be correlated with changes in excitability or contractility. This experiment was undertaken to measure changes in K+ fluxes during exposure to "toxic" or "therapeutic" concentrations of ouabain. In isolated rabbit atria "therapeutic" concentrations of ouabain decreased K42 loss as well as increased uptake of radioactive potassium. This may explain both the maintenance and increase in intracellular K+ observed by other investigators. "Toxic" concentrations of ouabain blocked K42 uptake and this alone may explain the effects of digitalis on intracellular K+ concentration. However, the inhibition of K+ uptake occurred later than the negative inotropic effect on contractility. This supports the previous assumption (Tuttle et al., 1961) that changes in intracellular K+ concentration or fluxes brought about by ouabain are not causally related to the inotropic effects of the drug.