Phosphoinositide metabolism and insulin secretion from isolated rat pancreatic islets.
AUTOR(ES)
Clements, R S
RESUMO
Since many cell types have been shown to respond to extracellular stimulation with a rapid increase in phosphatidylinositol turnover, the present studies were undertaken to determine whether carbohydrate-stimulated insulin secretion from the isolated rat pancreatic islet is accompanied by detectable alterations in the phosphatidylinositol metabolism of this tissue. We have demonstrated that rat pancreatic islets incubated with tritiated myo-inositol rapidly incorporate radioactivity into islet phosphatidylinositol. Incubation of prelabeled islets with elevated concentrations of carbohydrates which stimulate insulin secretion (D-glucose and D-mannose) results in a decrease in the recovery of lipid-bound radioactivity, whereas incubation with carbohydrates which do not stimulate insulin secretion (D-galactose and myo-inositol) has no effect upon the recovery of lipid-bound radioactivity. Within 2 min of exposure of prelabeled islets to elevated concentrations of D-glucose, a decrease in the recovery of [2-3H]myo-inositol-derived radioactivity in islet phosphatidylinositol can be demonstrated. When islets prelabeled with [2-3H]myo-inositol are perifused with elevated concentrations of D-glucose or D-mannose (but not D-galactose or myoinositol) a rapid and transient increase in the rate of extracellular release of water-soluble radioactivity is observed. Since a significant fraction of the radioactivity released under these conditions is in the form of myo-inositol phosphate, cyclic myo-inositol-1,2-phosphate, and glycerophosphorylmyo-inositol, it is presumably derived from the cleavage of labeled islet phosphatidylinositol. It is speculated that alterations in the metabolism of myo-inositol-containing phospholipids may have a functional role in the process of insulin secretion from the pancreatic beta cell.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=436702Documentos Relacionados
- Effects of vitamin A deficiency and repletion on rat insulin secretion in vivo and in vitro from isolated islets.
- Heterogeneity and compartmental properties of insulin storage and secretion in rat islets.
- Glucagon release from rat pancreatic islets. A combined morphological and functional approach.
- Possible role for calmodulin in insulin release. Studies with trifluoperazine in rat pancreatic islets.
- Rat amylin: cloning and tissue-specific expression in pancreatic islets.