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Science 16 June 1978:
Vol. 200. no. 4347, pp. 1287 - 1289
DOI: 10.1126/science.149369
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Articles

Science, Vol 200, Issue 4347, 1287-1289
Copyright © 1978 by American Association for the Advancement of Science

articles

Is pump stimulation associated with positive inotropy of the heart?

L Michael, BJ Pitts, and A Schwartz

A purified sodium and potassium dependent adenosinetriphosphatase isolated from cat heart was not stimulated by any concentration of ouabain that produced positive inotropy of cat papilliary muscle. Only inhibition of enzyme activity was observed. Concentrations of ouabain used ranged from 3.3 x 10(-10) molar to 5 x 10(-7) molar and produced an increased force of contraction without any evidence of toxicity. The results are inconsistent with a concept that stimulation of sodium pump activity is associated with positive inotropy.




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Science. ISSN 0036-8075 (print), 1095-9203 (online)