Abstract
Summary and Conclusions
1. Ouabain, in concentrations from 1 × 10-6 M to 5 × 10-5. M, was added to embryonic chick hearts whose oxygen consumption was being measured in the cartesian diver. Controls, in which Ringer, Locke, etc., was mixed with Ringer, Locke, etc., respectively, were also employed. 2. Ouabain, in concentrations from 1 × 10.6 M to 5 × 10-5 M, inclusive, caused a prompt increase in oxygen consumption, roughly proportional to concentration. 3. Ouabain, at a concentration of 5 × 10-5 M, caused an immediate increase in heart rate, and, after about 3 minutes, irregularities in the beat of the heart. 4. Ouabain, in a concentration of 1 × 10-6 M, did not produce irregularities and did not alter the heart rate. 5. Oxygen consumption, heart rate, and incidence of irregularities were not altered by mixing control solutions with control solutions. 6. Acetylcholine plus prostigmine increased, whereas atropine decreased the severity of the irregularities produced by ouabain, without appreciably altering the increase in oxygen consumption caused by ouabain. 7. The increase in oxygen consumption after ouabain is not directly related to changes in the beat of the heart.
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