Metabolic zonation in liver of diabetic rats. Zonal distribution of phosphoenolpyruvate carboxykinase, pyruvate kinase, glucose-6-phosphatase and succinate dehydrogenase.
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)
Miethke
H
H
Wittig
B
B
Nath
A
A
Zierz
S
S
Jungermann
K
K
D000818:Animals; D002458:Cell Fractionation / Q000379:methods; D002501:Centrifugation, Zonal; D003921:Diabetes Mellitus, Experimental / Q000097:blood / Q000201:enzymology* / Q000473:pathology; D005934:Glucagon / Q000097:blood; D005952:Glucose-6-Phosphatase / Q000032:analysis*; D007328:Insulin / Q000097:blood; D008099:Liver / Q000201:enzymology* / Q000648:ultrastructure; D008297:Male; D010729:Phosphoenolpyruvate Carboxykinase (GTP) / Q000032:analysis*; D011770:Pyruvate Kinase / Q000032:analysis*; D051381:Rats; D011919:Rats, Inbred Strains; D013347:Subcellular Fractions / Q000201:enzymology; D013385:Succinate Dehydrogenase / Q000032:analysis*
D007328:Insulin; D005934:Glucagon; D013385:Succinate Dehydrogenase; D011770:Pyruvate Kinase; D005952:Glucose-6-Phosphatase; D010729:Phosphoenolpyruvate Carboxykinase (GTP)