Studies on Glycolytic Enzymes: Glucose-6-Phosphatase, Phosphorylase and Phosphoglucomutase. Effect of Glucose Gycloacetoacetate (Hydrolysed).

Abstract

The activities of the hepatic glycolytic enzymes, glucose-6-phosphatase, phosphorylase and phosphoglucomutase have been found to be altered in disturbed carbohydrate metabolism. An increase in liver glucose-6-phosphatase activity has been reported in alloxan diabetic and fasting animals( 1-5). A parallelism between liver glycogen and activity of phosphoglucomutase in physiologic and pathologic conditions was indicated by Weber and Canter0 (6). An increase in hepatic phosphorylase in obese hyperglycemic mice( 7) and a decrease in fasting rats have been observed Glucose cycloacetoacetate (GCA) has been found to have an ameliorating effect in alloxan diabetes; it cured alloxan diabetes in rabbits when given with estrogen and reduced blood glucose concentration when given alone (9). As it has also been reported to maintain glycogen synthesis and breakdown in equilibrium in the liver( lo), it was considered interesting to study its effect on the activities of these hepatic enzymes in alloxan diabetic and fasting rats.Matmials and methods. Male albino rats weighing 100-150 g were divided into 5 groups as follows:Group I-Normal fed rats; Group 11-24 hr fasted rats; Group 111-24 hr fasted rats injected GCA(h) ; Group IV-Alloxan diabetic rats; and Group V-Alloxan diabetic rats injected GCA (h) .The animals were fed a normal diet of the following composition:-wheat flour 601%,. fats lo'%, protein 20%, salt mixture S%, yeast powder 5 %, throughout the experimental period. Rats were made diabetic by subcutaneous injection of alloxan monohydrate (dose . Some rats died in 5 to 7 days. Those surviving and having a blood glucose level above 200 mg/lOiO ml were used in the experiment. GCA prepared by the method of West( 11) as modified by Nath et al( 12) was hydrolyzed with 2 N HC1 for 201 minutes in a boiling water bath and extracted with ether to remove the resinous material formed. The aqueous solution was adjusted to pH 7.2 with 2 N NaOH. This was injected into the rats of Groups I11 and V intraperitoneally in 3 equal doses of 600 mg/kg at 10 a.m., 5 p.m. and again at 10 a.m. next morning. Two hours after the third injection, the rats were killed and their livers removed for determining the enzyme activities. The animals of Groups I1 and I11 were fasted for 24 hours before killing whereas the animals of other groups were fed. The rats were stunned, decapitated and bled. The livers were quickly excised, p l e d in a beaker standing on cracked ice, chilled for 5 minutes, blotted on filter paper and weighed. A 10% homogenate was prepaxed in ice cold water for glucose-6-phosphatase and phosphoglucomutase activity and in .1