AJP - Endocrinology and Metabolism, Vol 255, Issue 6 E843-E849, Copyright © 1988 by American Physiological Society
Glucose intolerance in thyrotoxic rats: role of insulin, glucagon, and epinephrine
T. Ikeda, O. Mokuda, M. Tominaga and H. Mashiba
First Department of Internal Medicine, Tottori University School of Medicine, Yonago, Japan.
To elucidate the possible role of insulin, glucagon, and epinephrine on
glucose intolerance in thyrotoxicosis, the secretion of insulin and
glucagon in vivo (glucose, arginine, and epinephrine infusion tests) and in
perfused pancreas and the hepatic action of insulin, glucagon, and
epinephrine in perfused liver were investigated in experimental thyrotoxic
rats (induced by thyroxine injection, 20 micrograms/kg sc, for 7 days). In
thyrotoxic rats, fasting blood glucose (87 +/- 5 mg/dl, mean +/- SD) and
plasma insulin (16 +/- 3 microU/ml) were significantly (P less than 0.001)
higher than those in controls (74 +/- 5 mg/dl and 8 +/- 1 microU/ml),
respectively. In glucose infusion test (0.5 g/kg iv), blood glucose, plasma
insulin, and glucagon responses in thyrotoxic rats were not significantly
different from those in controls. In arginine infusion test (5 mg/min for
20 min iv), the increments in blood glucose and plasma insulin after
arginine in thyrotoxic rats were not significantly different from those in
controls. Plasma glucagon response was almost the same in both groups. In
epinephrine infusion test (100 micrograms/kg iv), the increments in blood
glucose and plasma insulin in thyrotoxic rats were significantly greater
than those in controls. In perfused pancreas, insulin and glucagon
secretions in response to 16.7 mM glucose or 6.4 mM arginine in the
presence of 5.5 mM glucose in thyrotoxic rats were not different from those
in controls.(ABSTRACT TRUNCATED AT 250 WORDS)
