Abstract
Ouabain in concentrations of from 10-6 to 10-3M produced a sustained increase in the respiratory rate of cat heart slices. Such a stimulation could only be demonstrated after depression of the original respiratory rate by preincubation or by treatment with barbiturate. When the glycoside was added to undepressed slices the respiration was inhibited by all concentrations of ouabain from 10-6 to 10-3M.
Ouabain had no effect upon the oxidative or phosphorylative capacity of cat heart or guinea pig brain mitochondrial preparations, nor did the drug stimulate such mitochondrial preparations which had been depressed by barbiturate or calcium. The results are interpreted as indicating that the effects of ouabain on intact heart cells are mediated by some other means than a direct action upon oxidative enzymes per se.
Footnotes
- Received January 23, 1953.
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