Role of intrapancreatic ganglia in regulation of periodic insular secretions

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Abstract
The regulatory system responsible for insulin oscillations from the in vitro dog pancreas were studied 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 blockade (.beta.-bungarotoxin) was without effect on oscillations. The infusion of the postsynaptic nicotinic receptor antagonists, hexamethonium, .alpha.-bungarotoxin (ATX) or curarine, significantly altered the preinfusion oscillatory pattern of insulin release by reducing the period. Nicotine-stimulated insulin release was inhibited by ATX on a background of atropine, phentolamine and .beta.-bungarotoxin. Propranolol decreased nicotine-stimulated insulin release, which was further reduced by ATX. Nicotinic receptors may be present pre- and postsynaptically at the ganglionic level and presynaptically on sympathetic nerve axons. Ganglionic nicotinic receptors may be regulatory and that ganglia may serve as the pacemaker to regulate pancreatic hormone oscillations.