Effect of adrenalin,hydrocortisone, insulin,and dibutyryl-cyclic AMP on glycolysis and glycogenolysis in surviving liver splices from albino rats

Adrenalin, hydrocortisone, and dibutyryl-cyclic AMP inhibited glycolysis and glycogenolysis in surviving liver slices from albino rats. An inhibitory effect also was found when glucose-6-phosphate (G6P), but not fructore-1, 6-diphosphate, was used as the substrate for glycolysis. This indicates that activity of hexokinase and also, probably, of, phosphorylase and phosphofructokinase, in inhibited under the influence, of these hormones and dibutyrul-cyclic AMP. In a reconstituted cell-free system the hormone had no effect and dibutyryl-cyclic AMP inhibited hexokinase only. For the hormones to exert their effect interaction between them and the cell membrane was essential. Inhibition of glycogen and G6P breakdown to lactic acid in liver slices is not connected with the action of the hormones on the corresponding enzymes (phosphorylase and phosphofructokinase) directly through cyclic AMP and protein kinase. The results are evidence of an additional mechanism modifying the action of cyclic AMP on the activity of the above-mentioned enzymes. Insulin had no, effect in all cases.Laboratory of Biochemistry, Institute of Clinical and Experimental Medicine, Siberian Branch, Academy of Medical Sciences of the USSR, Novosibirsk. (Presented by Academician of the Academy of Medical Sciences of the USSR V. P. Kaznacheev.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 86, No. 11, pp. 541–544, November, 1978.