PT  - JOURNAL ARTICLE
AU  - NORTON J. GREENBERGER
AU  - RICHARD P. MacDERMOTT
AU  - JAMES F. MARTIN
AU  - SARADINDU DUTTA
TI  - INTESTINAL ABSORPTION OF SIX TRITIUM-LABELED DIGITALIS GLYCOSIDES IN RATS AND GUINEA PIGS
DP  - 1969 Jun 01
TA  - Journal of Pharmacology and Experimental Therapeutics
PG  - 265--273
VI  - 167
IP  - 2
4099  - http://jpet.aspetjournals.org/content/167/2/265.short
4100  - http://jpet.aspetjournals.org/content/167/2/265.full
SO  - J Pharmacol Exp Ther1969 Jun 01; 167
AB  - Relatively little attention has been directed toward the mechanism of the intestinal absorption of digitalis glycosides. In the present investigation the absorption of six tritium-labeled cardiac glycosides was studied in rats and guinea pigs utilizing isolated intestinal loops in vivo and everted duodenal and jejunal gut sacs in vitro. The nonpolar glycosides, digitoxin, digoxin and proscillaridin, were found to be absorbed more rapidly than the polar glycosides, ouabain, dihydroouabain and convallatoxol. Bile duct ligation did not affect the absorption of digitoxin from isolated intestinal loops in rats. The absorption of digitoxin was directly proportional to substrate concentration both in vivo and in vitro. In in vitro studies the transport of digitoxin was not affected by the presence of several metabolic inhibitors (dinitrophenol, iodoacetate, sodium azide), by the omission of glucose from the incubation medium or by anaerobic incubation conditions, indicating that the transport of digitoxin does not depend upon energy supplied by cellular metabolism. In addition, the transport of digitoxin was not inhibited by another cardiac glycoside, digoxin, suggesting that there are no specific transport sites that allow for competition between glycosides. These observations indicate that digitoxin is absorbed by a passive (nonsaturable) transport process. © 1969 by The Williams & Wilkins Co.