PT - JOURNAL ARTICLE AU - ARNOLD SCHWARTZ AU - JULIUS C. ALLEN AU - SHOICHI HARIGAYA TI - POSSIBLE INVOLVEMENT OF CARDIAC Na<sup>+</sup> , K<sup>+</sup>-ADENOSINE TRIPHOSPHATASE IN THE MECHANISM OF ACTION OF CARDIAC GLYCOSIDES DP - 1969 Jul 01 TA - Journal of Pharmacology and Experimental Therapeutics PG - 31--41 VI - 168 IP - 1 4099 - http://jpet.aspetjournals.org/content/168/1/31.short 4100 - http://jpet.aspetjournals.org/content/168/1/31.full SO - J Pharmacol Exp Ther1969 Jul 01; 168 AB - The effects of ouabain and digoxin on a cardiac Na+, K+-adenosine triphosphatase (Na+, K+-ATPase) from dog and beef were monitored with a continuous recording spectrophotometer. A time and temperature dependence of glycoside-induced inhibition was found. Increasing the time of enzyme exposure to the drug and increasing the temperature of incubation resulted in a significant enhancement of cardiac glycoside action. Half-maximal inhibitory concentration at 45°C and after 30-minute exposure was 0.025 µM for beef heart. The binding of H3-ouabain to the Na+ , K+-ATPase appeared to be related to the inhibitory effect of ouabain on Na+, K+-ATPase. An active cardiac relaxing system did not bind H3-digoxin or H3-ouabain, nor was Ca++ binding or uptake affected by a wide range of glycoside concentrations. Cardiac mitochondria were not affected by ouabain or digoxin. It is concluded that the Na+, K+-ATPase may be involved in the action of cardiac glycosides. © 1969, by The Williams &amp; Wilkins Company