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Albert Salehi

S Albert Salehi

Research team manager

Albert Salehi

TPN-evoked dysfunction of islet lysosomal activity mediates impairment of glucose-stimulated insulin release


  • S Albert Salehi
  • Bo-Guang Fan
  • Mats Ekelund
  • Gunnar Nordin
  • Ingmar Lundquist

Summary, in English

We examined the relation between nutrient-stimulated insulin secretion and the islet lysosome acid glucan-1,4-alpha-glucosidase system in rats undergoing total parenteral nutrition (TPN). During TPN treatment, serum glucose was normal, but free fatty acids, triglycerides, and cholesterol were elevated. Islets from TPN-infused rats showed increased basal insulin release, a normal insulin response to cholinergic stimulation but a greatly impaired response when stimulated by glucose or alpha-ketoisocaproic acid. This impairment of glucose-stimulated insulin release was only slightly ameliorated by the carnitine palmitoyltransferase 1 inhibitor etomoxir. However, in parallel with the impaired insulin response to glucose, islets from TPN-infused animals displayed reduced activities of islet lysosomal enzymes including the acid glucan-1,4-alpha-glucosidase, a putative key enzyme in nutrient-stimulated insulin release. By comparison, the same lysosomal enzymes were increased in liver tissue. Furthermore, in intact control islets, the pseudotetrasaccharide acarbose, a selective inhibitor of acid alpha-glucosidehydrolases, dose dependently suppressed islet acid glucan-1,4-alpha-glucosidase and acid alpha-glucosidase activities in parallel with an inhibitory action on glucose-stimulated insulin secretion. By contrast, when incubated with intact TPN islets, acarbose had no effect on either enzyme activity or glucose-induced insulin release. Moreover, when acarbose was added directly to TPN islet homogenates, the dose-response effect on the catalytic activity of the acid alpha-glucosidehydrolases was shifted to the right compared with control homogenates. We suggest that a general dysfunction of the islet lysosomal/vacuolar system and reduced catalytic activities of acid glucan-1,4-alpha-glucosidase and acid alpha-glucosidase may be important defects behind the impairment of the transduction mechanisms for nutrient-stimulated insulin release in islets from TPN-infused rats.


  • Islet cell physiology
  • Surgery (Lund)

Publishing year







American Journal of Physiology: Endocrinology and Metabolism





Document type

Journal article


American Physiological Society


  • Physiology



Research group

  • Islet cell physiology


  • ISSN: 1522-1555