During perfusion with a glucose concentration of 150 mg/100 ml, infusions of l-epinephrine, l-norepinephrine, and d-l-isoproterenol at physiological concentrations of 2 ng/ml for 9 min stimulated secretion of glucagon in a monophasic response pattern, in contrast to the biphasic response normally encountered after glucagon releasing stimuli as previously reported from our laboratory (1971. J. C...

OBJECTIVE We tested the hypothesis that an increase in insulin per se, i.e., in the absence of zinc, suppresses glucagon secretion during euglycemia and that a decrease in insulin per se stimulates glucagon secretion during hypoglycemia in humans. RESEARCH DESIGN AND METHODS We measured plasma glucagon concentrations in patients with type 1 diabetes infused with the zinc-free insulin glulisin...

OBJECTIVE Somatostatin (SST) is secreted by islet delta-cells and by extraislet neuroendocrine cells. SST receptors have been identified on alpha- and beta-cells, and exogenous SST inhibits insulin and glucagon secretion, consistent with a role for SST in regulating alpha- and beta-cell function. However, the specific intraislet function of delta-cell SST remains uncertain. We have used Sst(-/-...

Type 2 diabetes mellitus (T2DM) results from insulin resistance and β-cell dysfunction, in the setting of hyperglucagonemia. Glucagon is a 29 amino acid peptide hormone, which is secreted from pancreatic α cells: excessively high circulating levels of glucagon lead to excessive hepatic glucose output. We investigated if α-cell numbers increase in T2DM and what factor (s) regulate α-cell turnove...

BACKGROUND Ingested proteins are known to stimulate a rise in insulin and glucagon concentrations. In our effort to explain this effect, we have begun to measure the effect of individual amino acids. OBJECTIVES The objectives were to determine the effect of lysine ingestion on insulin and glucagon concentrations and whether the effect is moderated by glucose ingestion. DESIGN Thirteen healt...

OBJECTIVE The intraislet insulin hypothesis proposes that glucagon secretion during hypoglycemia is triggered by a decrease in intraislet insulin secretion. A more recent hypothesis based on in vivo data from hypoglycemic rats is that it is the decrease in zinc cosecreted with insulin from beta-cells, rather than the decrease in insulin itself, that signals glucagon secretion from alpha-cells d...

PURPOSE In animal models, it has been shown that the retina can use the defocus of the projected image to control emmetropization. Glucagon may be involved in the sign of defocus detection, at least in chickens. Since glucagon and insulin often have opposite effects in metabolic pathways, the effect of insulin on eye growth was investigated. METHODS Chicks were treated with either positive or...

Obesity is associated with intrahepatic inflammation that promotes insulin resistance and type 2 diabetes. Tumor necrosis factor receptor-associated factor (TRAF)2 is a key adaptor molecule that is known to mediate proinflammatory cytokine signaling in immune cells; however, its metabolic function remains unclear. We examined the role of hepatic TRAF2 in the regulation of insulin sensitivity an...

Previous studies have shown that whole body deletion of the glucagon receptor suppresses the ability of starvation to increase hepatic fibroblast growth factor 21 (FGF21) expression and plasma FGF21 concentration. Here, we investigate the mechanism by which glucagon receptor activation increases hepatic FGF21 production. Incubating primary rat hepatocyte cultures with glucagon, dibutyryl cAMP o...

The aim of the present experiments was to determine the effects of basal glucagon on glucose production after induction of prolonged insulin lack in normal conscious dogs fasted overnight. A selective deficiency of insulin or a combined deficiency of both pancreatic hormones was created by infusing somatostatin alone or in combination with an intraportal replacement infusion of glucagon. Glucos...