Glucose-induced time-dependent potentiation of insulin release, but not islet blood perfusion, in anesthetized rats.
BACKGROUND
Repeated administration of glucose in vivo leads to a time-dependent potentiation of insulin release. Glucose is also known to stimulate pancreatic islet blood flow, but whether this is associated with a time-dependent potentiation is unknown. We therefore repeatedly administered glucose to anesthetized rats and evaluated effects on insulin release and islet blood flow.


METHODS
Male Wistar-Furth rats, anesthetized with thiobutabarbital, were injected intravenously with 1 ml of saline or glucose at times 0, 30 and 60 min. The combinations used were saline + saline + saline (SSS), glucose + saline + saline (GSS), saline + saline + glucose (SSG) and glucose + glucose + glucose (GGG). Regional organ blood flow values were measured 3 min after the final injection with a microsphere technique, and at this time also serum insulin concentrations were determined with ELISA.


RESULTS
Serum insulin concentrations as well as total pancreatic, pancreatic islet and duodenal blood flow were higher in SSG and GGG-treated rats when compared to those given SSS and GSS. However, only insulin concentrations, not blood flow values, were higher in GGG rats when compared to SSG animals.


CONCLUSIONS
Glucose-induced time-dependent potentiation of insulin release occurs in vivo in thiobutabarbital-anesthetized rats, but is not associated with a further increase in islet blood flow.
Department of Medical Cell Biology, Uppsala University, Uppsala, Sweden. Leif.Jansson@mcb.uu.se
Leif
L
Jansson
Birgitta
B
Bodin
Orjan
O
Källskog
D000818:Animals; D001786:Blood Glucose / Q000032:analysis; D005947:Glucose / Q000008:administration & dosage / Q000494:pharmacology*; D007328:Insulin / Q000097:blood / Q000378:metabolism*; D007515:Islets of Langerhans / Q000098:blood supply / Q000187:drug effects* / Q000378:metabolism; D008297:Male; D051381:Rats; D017208:Rats, Wistar
D001786:Blood Glucose; D007328:Insulin; D005947:Glucose