Abstract
The effect of ouabain on the oxygen consumption, the contractility and the concentrations of ATP and PC of cat papillary muscles have been measured simultaneously. Ouabain has been found to increase in contractility and the oxygen consumption while decreasing the concentrations of ATP and PC.
Contractility is increased by ouabain before any effect on the oxygen consumption and on the concentrations of ATP and PC becomes manifest. The marked increase in the oxygen consumption is always accompanied by a concomitant decrease in the concentrations of ATP and PC. These metabolic effects of ouabain are clearly demonstrable in both contracting and noncontracting papillary muscles.
The effects of glucose, pyruvate and succinate have been investigated on muscles contracting in substrate-free Krebs-Ringer-phosphate media. Glucose has no marked effect on QO2 and contractility. Pyruvate increases the oxygen consumption, the content of ATP and PC and the contractility of muscle. However, succinate does not improve contractility in spite of the increase in the oxygen consumption and in the content of ATP and PC following the addition of this substrate. The effects of ouabain on papillary muscles are similar in all media used regardless of the presence or absence of the substrates.
Footnotes
- Received November 9, 1959.
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