Evidence for the presence of glucose cycling in pancreatic islets of the ob/ob mouse.
Pancreatic islets from ob/ob mice incubated with 3H2O and 5.5 mM glucose formed 3H-labeled glucose, 74 picoatoms incorporated/islet/h. Sixty-three percent of the 3H was bound to carbon 2 of the glucose. The amount of glucose-6-P dephosphorylated to glucose, determined from this incorporation, was 48 pmol/islet/h. Glucose utilization, measured by the formation of 3H2O from [5-3H]glucose, was 72 pmol/islet/h. The amount of glucose dephosphorylated was then about 40% of that phosphorylated. Thus, glucose-6-P is dephosphorylated to glucose to a significant extent by intact islets in vitro and presumably by the beta cells of the islets. The extent of this glucose cycling, i.e. glucose----glucose-6-P----glucose, may play a role in determining the extent of glucose-induced insulin secretion.
Khan
A
A
Department of Endocrinology, Karolinska Hospital, Stockholm, Sweden.
Chandramouli
V
V
Ostenson
C G
CG
Ahrén
B
B
Schumann
W C
WC
Löw
H
H
Landau
B R
BR
Efendić
S
S
D000818:Animals; D001834:Body Water / Q000378:metabolism; D002250:Carbon Radioisotopes; D005947:Glucose / Q000378:metabolism*; D066298:In Vitro Techniques; D007515:Islets of Langerhans / Q000378:metabolism*; D051379:Mice; D008820:Mice, Obese; D010766:Phosphorylation; D011865:Radioisotope Dilution Technique; D014316:Tritium
D002250:Carbon Radioisotopes; D014316:Tritium; D005947:Glucose