John I. Stagner

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Canine pancreata were perfused in vitro to examine whether hormone cycles could be demonstrated without hepatic or central nervous influence. Insulin, glucagon, and somatostatin demonstrated regular sustained cyclic secretion from the in vitro canine pancreas. Oscillations were noted for over 200 min during the infusion of a constant glucose concentration.(More)
BACKGROUND The stimulating effects of insulin on the exocrine pancreas are well known. The effects of other islet hormones, however, are controversial. The aim of the present study was to determine whether the islet-acinar axis, as a whole, is stimulatory or inhibitory. Because we have shown that retrograde perfusion reverses the islet-acinar directed(More)
In order to determine whether microvascular blood flow is important in the regulation of intra-islet cellular interactions, rat pancreata were isolated and perfused in vitro, both anterogradely or retrogradely, with and without anti-insulin or anti-somatostatin gamma-globulin. Expressed as percent change, anterograde infusion of insulin antibody increased(More)
The vascular order of pancreatic islet cellular perfusion is important in the intraislet regulation of hormone secretion. Establishment of the sequence of interaction is fundamental to understanding the physiology and pathophysiology of the human islet. Intraislet insulin from the beta-cell regulates both net hormone secretion and pulsatile secretion from(More)
The regulatory system responsible for insulin oscillations from the in vitro pancreas is unknown. To test the hypothesis that intrapancreatic ganglia are the pacemaker or driver of the oscillations, combined nicotinic, muscarinic, and adrenergic antagonists were infused. Combined muscarinic, alpha- and beta-adrenergic, and presynaptic nicotinic receptor(More)
The impairment of glucose-potentiated insulin secretion present in non-insulin-dependent diabetes mellitus (NIDDM) can be approximated in normal subjects by an epinephrine infusion. Therefore, we sought to determine the role of the endogenous sympathetic nervous system in glucose-potentiated insulin secretion in both NIDDM (n = 6) and normal (n = 6)(More)
The possible role of the D cell in the regulation of islet hormone secretion has been controversial for many years. It is known that the D cells characteristically reside in the islet mantle interspaced among A cells. We have shown by the anterograde and retrograde infusion of antibody directed against insulin, glucagon, or somatostatin into the isolated(More)
In the canine pancreas alpha and beta adrenergic receptors exist on D cells with α stimulation inhibiting and β stimulation increasing somatostatin release. There are no dopaminergic receptors on D cells. Stimulation of muscarinic receptors causes mild inhibition of somatostatin secretion. Autonomic receptors on the D cell may be physiologically stimulated(More)
Biodegradable pellets releasing 20 ng/day of endothelial cell growth factor alpha (alpha ECGF) or a- or b-fibroblast growth factor (FGF) and 90 micrograms/day of heparin were implanted beneath the renal capsule in rats and dogs and the muscularis/serosal border of the pyloric stomach in dogs to test for angiogenesis in a potential pancreatic islet(More)
The in vitro canine pancreas produces an oscillatory pattern of insulin secretion during a constant glucose concentration despite the lack of external nervous modulation or recirculating hormone feedback. The normal period of insulin fluctuations (7.4 +/- 0.34 min) is unaffected by combined adrenergic and cholinergic blockade by 5 microM atropine, 4 microM(More)