Glucose cycling in islets from healthy and diabetic rats.
Pancreatic islets from healthy (control) and neonatally streptozocin-induced diabetic (STZ-D) rats, a model for non-insulin-dependent diabetes mellitus, were incubated with 3H2O and 5.5 or 16.7 mM glucose. At 5.5 mM glucose, no detectable [3H]glucose was formed. At 16.7 mM, 2.2 patom.islet-1.h-1 of 3H was incorporated into glucose by the control islets and 5.4 patom.islet-1.h-1 by STZ-D islets. About 75% of the 3H was bound to carbon-2 of the glucose. Glucose utilization was 35.3 pmol.islet-1.h-1 by the control and 19.0 pmol.islet-1.h-1 by the STZ-D islets. Therefore, 4.5% of the glucose-6-phosphate formed by the control islets and 15.7% by the STZ-D islets was dephosphorylated. This presumably occurred in the beta-cells of the islets catalyzed by glucose-6-phosphatase. An increased glucose cycling, i.e., glucose----glucose-6-phosphate----glucose, in islets of STZ-D rats may contribute to the decreased insulin secretion found in these animals.
Khan
A
A
Department of Endocrinology, Karolinska Hospital, Stockholm, Sweden.
Chandramouli
V
V
Ostenson
C G
CG
Löw
H
H
Landau
B R
BR
Efendić
S
S
D000818:Animals; D003921:Diabetes Mellitus, Experimental / Q000378:metabolism*; D005260:Female; D005947:Glucose / Q000378:metabolism* / Q000494:pharmacology; D007328:Insulin / Q000378:metabolism; D000078790:Insulin Secretion; D007515:Islets of Langerhans / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D011865:Radioisotope Dilution Technique; D051381:Rats; D011919:Rats, Inbred Strains; D012016:Reference Values; D014316:Tritium
D007328:Insulin; D014316:Tritium; D005947:Glucose