The influence of intraperitoneal administration of aminophylline on the rate of hepatic glucose production and peripheral uptake (Ra and Rd) was studied in normal and in adrenodemedullated and reserpinized rats by using the primed constant infusion of glucose 2 3H. In normal rats, a dose of 100 mg/kilogram of aminophylline produced a marked increase of Ra and Rd. Since Ra rose more rapidly than Rd did initially, hyperglycemia developed. Thereafter, glucose production and uptake increased to nearly the same extent, and a new steady state was reached at plasma glucose levels almost twice those of the baseline. Smaller and transient modifications were observed after tha administration of 20 mg/kilogram of aminophylline. With the higher dose, insulin levels markedly rose (reaching a 10 fold peak above the basal value) while minor increments were observed with the lower dose. In a group of normal rats which were given glucose (10 mg/kilogram/minute) in order to achieve a degree of hyperglycemia comparable to that brought about by the higher dose of aminophylline, an almost identical enhancement of glucose uptake was recorded. Insulin levels were much higher in aminophylline treated rats as compared to normal rats. From these findings it was concluded that aminophylline induces resistance to insulin effects. When aminophylline was injected into demedullated rats pretreated with reserpine, at the dose of 100 mg/kilogram, a marked enhancement of Ra, and consequently of glycemia, was recorded initially; later, severe hypoglycemia developed depending on both a progressive exhaustion of hepatic glucose production and a marked increase of glucose utilization. Insulin levels dramatically increased these experiments. These results suggest that aminophylline directly increases glucose production by liver and insulin secretion. The simultaneous activation of the sympathetic system blunts the insulin response and counteracts the restraining effect of insulin on the liver and also the stimulatory effect of insulin on overall uptake.
|Number of pages||8|
|Publication status||Published - 1975|
ASJC Scopus subject areas
- Internal Medicine
- Endocrinology, Diabetes and Metabolism