OBJECTIVE To examine the effect of aging on insulin secretion (first- and second-phase insulin release) and insulin sensitivity in people with normal glucose tolerance (NGT) or impaired glucose tolerance (IGT). RESEARCH DESIGN AND METHODS First- and second-phase insulin secretion and insulin sensitivity were assessed in hyperglycemic clamp experiments in 266 individuals with NGT and 130 indiv...

In an answer to the challenge of enzymatic instability and low oral bioavailability of proteins/peptides, a new type of drug-delivery vesicle has been developed. The preparation, based on sodium dodecyl sulfate (SDS) and β-cyclodextrin (β-CD) embedded in chitosan gel, was used to successfully deliver the model drug-insulin. The self-assembled SDS/β-CD vesicles were prepared and characterized by...

incubated in the presence of an excess of insulin (approx. 3pg of insulin/ml). Glucosestimulated membranes can release approx. 1500ng of insulin/ml before saturation of glucose-generated 8-granule-binding sites takes place at 60min incubation. When glucose 6-phosphate was added no further release of insulin took place despite the availability of 1.5pg of insulin/ml in 8-granules in the supernat...

Westerlund, J. 2000. Pulsatile insulin release from single islets of Langerhans. Acta Universitatis Upsaliensis. Comprehensive Summaries of Uppsala Dissertations from the Faculty of Medicine 945. 49 pp. Uppsala. ISBN 91-554-4782-1 Insulin release from single islets of Langerhans is pulsatile. The secretory activities of the islets in the pancreas are coordinated resulting in plasma insulin osci...

Despite the urgent need for assays to visualize insulin secretion there is to date no reliable method available for measuring insulin release from single cells. To address this need, we developed a genetically encoded reporter termed RINS1 based on proinsulin superfolder GFP (sfGFP) and mCherry fusions for monitoring insulin secretion. RINS1 expression in MIN6 β cells resulted in proper process...

The current state of the HISS (hepatic insulin sensitizing substance) hypothesis is briefly outlined. In the postmeal absorptive state, 50-60% of the glucose storage action of insulin is accounted for by the actions of HISS released from the liver and acting on skeletal muscle. Hepatic parasympathetic nerves permissively regulate the ability of a pulse of insulin to release HISS, thereby potent...

Insulin activates insulin receptors (InsRs) in the hypothalamus to signal satiety after a meal. However, the rising incidence of obesity, which results in chronically elevated insulin levels, implies that insulin may also act in brain centres that regulate motivation and reward. We report here that insulin can amplify action potential-dependent dopamine (DA) release in the nucleus accumbens (NA...

An in vitro system for perifusion of rat pancreatic islets has been utilized to define the effects of cholinergic agents on the dynamics of insulin release. In the absence of glucose the effects of either acetylcholine or acetyl-beta-methylcholine were minimal at concentrations up to 10(-5) mM. In the presence of low glucose concentration (2.4 mM), both of the muscarinic agents produced dose-de...