Hypercalcemic effect of insulin in thyroparathyroidectomized alloxan-treated rats.
The acute effect of a hypoglycaemic dose of 0.5 U/100 g BW insulin administered intramuscularly on calcium metabolism was investigated in fasted alloxan-treated rats. It was found that the hypercalcaemic effect of insulin was evident only in thyroparathyroidectomized (TPTX) and not in parathyroidectomized (PTX) rats. A subcutaneous administration of 180 MRC mU/100 g BW calcitonin abolished the calcium raising effect of insulin in TPTX rats suggesting a protective role of calcitonin against insulin action in intact rats. In an attempt to elucidate the mechanism of the calcium raising effect of insulin 45Ca administered intravenously was used to indicate the movement of calcium from the plasma pool. Insulin administration delayed the plasma 45Ca disappearance rate but had no effect on bone 45Ca uptake within 120 min. In contrast, insulin administration resulted in a 31% reduction of urinary 45Ca excretion while the urine volume remained unchanged. However, the insulin-induced reduction of urinary calcium excretion could not totally account for the calcium raising effect of insulin in TPTX animals.
D000818:Animals; D001842:Bone and Bones / Q000378:metabolism; D002118:Calcium / Q000097:blood / Q000378:metabolism* / Q000652:urine; D003921:Diabetes Mellitus, Experimental / Q000503:physiopathology*; D007328:Insulin / Q000494:pharmacology*; D007668:Kidney / Q000502:physiology; D010280:Parathyroid Glands / Q000502:physiology; D051381:Rats; D013961:Thyroid Gland / Q000502:physiology
D007328:Insulin; D002118:Calcium