A Rabbit Serum Calcium Lowering Factor from the Pituitary

[摘要] A factor has been shown to exist in ACTH fractions of porcine pituitaries which lowers serum calcium levels markedly when injected intramuscularly in the fasting rabbit. The lowest value is usually reached in 1.5-2.5 hr. and returns to normal in 5-6 hr.It has been demonstrated that the activity of this material is independent of the ACTH activity of the preparation and is distinct from the pituitary hormones TSH, LTH, STH, or oxytocin. This factor can lower serum calcium levels in rabbits to as low as 50% of its initial value, producing tetany and convulsions.It has also been demonstrated that the action of this material is not mediated through the release of 1-adrenaline, 1-noradrenaline, insulin, glucagon, ascorbic acid, cortisone, hydrocortisone, or corticosterone, all of which substances are without significant effect. Parathormone raises serum calcium levels slowly in the rabbit. Commercial vasopressin preparations are active in lowering serum calcium levels but not to as low a level as the ACTH preparations.It has also been demonstrated that under stress the rabbit's serum calcium is spontaneously lowered to a slight degrree (10%).

[学科分类] 过敏症与临床免疫学