Abstract
In order to elucidate the effect of thyroid hormone on endocrine pancreatic functions, investigations were made of the dynamics of insulin and glucagon in intravenous glucose tolerance tests (IV-GTT), arginine tolerance tests (ATT) and perfusion studies of the isolated pancreas in rats treated with L-thyroxine (80 mg/kg i.p. inj.) for 14 days.
In IV-GTT, insulin secretion was markedly decreased, but glucose intolerance did not occur. In ATT, increased insulin release was observed. However, the insulin responses to glucose and arginine from perfused rat pancreas were not changed. The glucagon secretions in these experiments were not changed at all.
The above results suggest that thyroxine exerts a strong effect on insulin secretion in the rat in vivo, but has no effect on glucagon secretion.
