1. Metabolic zonation in liver of diabetic rats. Zonal distribution of phosphoenolpyruvate carboxykinase, pyruvate kinase, glucose-6-phosphatase and succinate dehydrogenase.
- Author
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Miethke H, Wittig B, Nath A, Zierz S, and Jungermann K
- Subjects
- Animals, Cell Fractionation methods, Centrifugation, Zonal, Diabetes Mellitus, Experimental blood, Diabetes Mellitus, Experimental pathology, Glucagon blood, Insulin blood, Liver ultrastructure, Male, Rats, Rats, Inbred Strains, Subcellular Fractions enzymology, Diabetes Mellitus, Experimental enzymology, Glucose-6-Phosphatase analysis, Liver enzymology, Phosphoenolpyruvate Carboxykinase (GTP) analysis, Pyruvate Kinase analysis, Succinate Dehydrogenase analysis
- Abstract
The activities and zonal distribution of key enzymes of carbohydrate metabolism were studied in livers of diabetic rats. 48 h after alloxan treatment the following alterations were observed, intermediate values being reached after 24 h: Blood glucose, acetoacetate and beta-hydroxybutyrate were increased to more than 500%; liver glycogen was reduced to about 10%. Portal vein insulin was reduced to below 10%, portal glucagon was increased to almost 200%. The glucogenic enzymes phosphoenolpyruvate carboxykinase and glucose-6-phosphatase were enhanced to 320% and 150%, respectively. The glycolytic enzymes glucokinase and pyruvate kinase L (differentiated from the M2 isoenzyme with a specific anti-L-antibody) were lowered to 50% and 75%, respectively. The citrate cycle enzyme succinate dehydrogenase remained unchanged. The normal periportal to perivenous gradient of phosphoenolpyruvate carboxykinase of about 3:1, as measured in microdissected tissue samples, was enhanced to about 4:1 with activities elevated to 230% and 190%, respectively, in the two zones. The normal periportal to perivenous gradient of pyruvate kinase L of about 1:1.7, as determined with the microdissection technique, was reduced to about 1:1.4 with levels lowered to 55% and 45%, respectively, in the two zones. The even zonal distribution of pyruvate kinase M2 remained unaltered.(ABSTRACT TRUNCATED AT 250 WORDS)
- Published
- 1985
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