Abstract
The aim of the project was to develop an immunoassay for glucagon and to use it to investigate the possible role of glucagon in 2-deoxy-glucose (2DG) induced hyperglycaemia. The radioimmunoassay work was directed to producing glucagon antiserum of sufficient quality for routine radioimmunoassay. This was accomplished by immunising 6 rabbits, one of which produced an antiserum with a final titre of 1/160,000 and an affinity constant [Ka] of 1. 9 x 10 9 L/M resulting in an assay with a sensitivity of 100 pg/ml. The possible role of glucagon as mediator in 2DG-induced hyperglycaemia was studied under various experimental conditions in normal rats, and in normal and glucagon-immunised rabbits. Somatostatin which caused a fall in blood glucose concentration in control rats did not prevent the appearance of 2DG-induced hyperglycaemia. Glucagon-immunised rabbits showed only a very small rise in blood glucose and plasma insulin when given exogenous glucagon (5 ug/kg b. w. ) but had a normal hyperglycaemic response to 2DG. These data suggest that glucagon is not essential for the production of 2DG-induced hyperglycaemia. The effect of a variety of adrenergic blocking agents on 2DG-induced hyperglycaemia was studied. At the dose levels used, none of the short term adrenergic blockers were effective in abolishing the rise in blood glucose, though 2 of the blockers were effective in abolishing the hyperglycaemic effect of exogenous adrenaline. The possibility that direct innervation of the liver adrenergic nerves is responsible for the observed rise in blood glucose has not been excluded and indeed seems likely on the evidence available. Finally, metabolic studies were carried out to investigate the fate of injected 2DG, in the rat, using tritiated 2DG. Over 50% of the administered dose was excreted unchanged in the urine within 24 hours; the rest was unaccounted for.