PT - JOURNAL ARTICLE AU - J. KYPSON AU - L. TRINER AU - G. G. NAHAS TI - THE EFFECTS OF CARDIAC GLYCOSIDES AND THEIR INTERACTION WITH CATECHOLAMINES ON GLYCOLYSIS AND GLYCOGENOLYSIS IN SKELETAL MUSCLE DP - 1968 Nov 01 TA - Journal of Pharmacology and Experimental Therapeutics PG - 22--30 VI - 164 IP - 1 4099 - http://jpet.aspetjournals.org/content/164/1/22.short 4100 - http://jpet.aspetjournals.org/content/164/1/22.full SO - J Pharmacol Exp Ther1968 Nov 01; 164 AB - Diaphragm muscles from Sherman rats were incubated in Krebs-Ringer phosphate buffer at pH 7.4 and a concentration of either 100 or 200 mg/100 ml glucose. In the presence of ouabain (10-4M) there were increased glucose uptake and glycogen content of muscle and a decreased lactate production combined with an increased. pyruvate concentration in the medium. In some experiments, C14-labeled glucose was added to the medium. During incubation with ouabain, the production of C14O2 from glucose was lower than in control, while O2 consumption was not changed. In the presence of ouabain, there was an accumulation of glucose-6-phosphate and fructose-6-phosphate and a decrease of fructose-1, 6-diphosphate. However, there was no accumulation of glucose-6-phosphate and fructose-6-phosphate when glucose was omitted from the medium. When twice the amount of phosphate was used in the medium, the effect of a similar dose of ouabain on lactate production and glycogen content was much less than that observed in medium containing the normal concentration of phosphate. Similar changes in glucose uptake, glycogen content of muscle and lactate and pyruvate production were observed with digitoxin (10-5 M). When glycolysis and glycogenolysis were stimulated by epinephrine (10-5M), norepinephrine (10-5M) or the dibutyryl derivative of cyclic 3',5'-adenosine monophosphate (10-3 M), digitoxin (10-5 M) inhibited the effects of these drugs on glycogen breakdown and lactate production. These findings indicate that phosphofructokinase and phosphorylase are involved in the inhibition of the glycolytic pathway caused by these concentrations of cardiac glycosides. © 1968, by The Williams & Wilkins Company