Comparison of metabolic effects of glucagon and calcitonin and assessment of direct effect of glucagon on calcitonin level in athyroid man.

The effect of intramuscular administration of glucagon (Glg) and calcitonin (Ct) on the pattern of serum calcium (Ca), in organic phosphorus (P), blood glucose (BS), immunoreactive insulin (IRI) and growth hormone (GH) was investigate in 14 patients after total thyroid ablation during replacement therapy. In seven patients the pattern of Ct after Glg administration was assessed in the same conditions. Both hormones induced a prompt and marked decrease of Ca with out any differences between effect of Glg and Ct. The decline of P due to Glg is more rapid and marked than the due to Ct, the difference being significant from 60 to 120 min. Glg caused a rapid and marked rise of BS and IRI with a tendency toward normalization up to 180 min, GH rose significantly from 120 to 180 min. The changes of BS and IRI due to Ct were slow and less marked, but prolonged: level of BS increased and that of IRI decreased. No effect of Ct administration on GH was recorded. In general, neither the effects of Glg nor those of Ct were influenced by hypothyroidism. This fact may be of importance for use of Glg in testing GH reserve in hypothyroidism. Ct after Glg administration in athyroid patients failed to exhibit any significant changes. Thus our results support the assumption about similar and independent action of Glg and Ct on calcium and phosphate homeostasis and different effects of both hormones on glucose metabolism.

Acute effect of large doses of calcitonin on calcium, magnesium and inorganic phosphate levels in rat serum in correlation to differences in thryroid function.

The acute effect of pharmacological doses of porcine calcitonin were studied on the calcium, inorganic phosphorus and magnesium level in correlation to thyroid function in experimental rats. In every case, and with all three doses, the serum calcium and inorganic phosphorus level fell significantly within 60 minutes after calcitonin administration. The drop in both minerals was most pronounced in the group with experimental hyperthyroidism, in which all different doses had the same effect. In experimental hypothyroidism, the decrease was correlated to the dose. In the case of the serum magnesium level, a statistically significant drop was observed in animals with hyperthyroidism after the two largest doses of calcitonin, while only a mild increase occurred in animals with hypothyroidism after the smallest dose. None of the doses of calcitonin affected the magnesium level in animals with normal thyroid function.

Effect of 6-azauridine on calcium metabolism in rats.

After 12 days of intramuscular administration of 6-azauridine (500 mg/kg b.w.) rats displayed a significant decrease in plasma calcium, inorganic phosphorus, and total hydroxyproline levels and alkaline and acid phosphatase activity. The biological method employed revealed no changes in calcitonin activity. 6-Azauridine reduced the citric acid concentration in the kidneys, liver, heart and bones. Alkaline phosphatase activity in the kidneys, heart and liver was unaffected. The results indicate that 6-azauridine inhibits calcium resorption from the bones and interferes with collagen synthesis. It cannot be ruled out that the described changes are elicited by the antimetabolic effect of this cytostatic drug.