THE INFLUENCE OF OUABAIN ON THE CONTRACTION OF STRIATED MUSCLE

¹ Department of Pharmacology, Cornell University Medical College, New York City

Ouabain in a concentration of 1 part in a million causes a characteristic series of changes in the contraction of the isolated frog's sartorius muscle. These changes, which occur while the muscle is in an atmosphere of oxygen after removal from the ouabain solution, are as follows : Initially there is a gradual increase in twitch tension (T) and initial heat production (H) without change in the efficiency (T/H). This is followed by an abrupt fall in tension and heat with a drop in the efficiency of contraction, and finally by complete loss of excitability.

These changes are reversible, there being very rapid recovery when the muscle is immersed in Ringer's solution. Moreover toxic effects do not develop while the muscle is kept in a oubain-Ringer's solution and after they have developed, reimmersion in the ouabain-Ringer's solution which produced them is as effective as Ringer's solution alone in bringing about a return to normal.

It is concluded that the changes described are due to the formation or liberation of some substance which readily diffuses from the muscle, and it is pointed out that these changes are consistent with those caused by the escape of potassium from the cell.

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