Effect of Total Thyroidectomy on Response to Injection of Adrenalin

Abstract

Since Elliot's work in 1907, the increased sensitivity to adrenalin in vessels deprived of sympathetic innervation has been well known. Clinical observations on patients following total removal of the thyroid have suggested a close dependency of adrenalin efficiency on the presence of thyroid hormone. The injection of adrenalin in patients deprived of thyroid secretion seemed to produce less vasoconstriction. This diminished action of adrenalin was very striking in limbs rendered especially sensitive to adrenalin by sympathectomy. Dogs were trained to stand quietly in a light overhead harness. Skin temperature curves were made at the same time of each fore leg by means of thermocouples attached to the skin. A number of such skin temperature curves under standard conditions revealed no difference between the fore legs. Being thus assured of a proper control, the sympathetic fibers supplying the left leg were destroyed by the removal of the stellate and each adjoining ganglion above and below. After allowing adequate time for the degeneration of the post-ganglionic fibers, determinations by the thermocouples revealed the customary 4° to 5° difference in temperature between the 2 legs. Skin temperature curves were now taken simultaneously on the 2 forelegs following an intravenous injection of a 1-20,000 solution of adrenalin chloride. The injections caused consistently a much greater and more prolonged fall in temperature on the operated side. When a number of similar curves were accumulated under identical standard conditions, the dogs were subjected to total thyroidectomy. After recovery and during the next 8 months temperature changes in both fore legs were again recorded following adrenalin injection. The post-thyroidectomy curves showed a great loss in the sensitivity of the sympathectomized vessels to adrenalin. In the dogs deprived of thyroid secretion the former prompt pressor response and resulting abrupt and prolonged fall of temperature on the operated side was almost entirely abolished. The curves for the intact limb were but little changed by total thyroidectomy. These experiments served to confirm our clinical impressions of the direct relationship between the thyroid hormone and the effectiveness of circulating adrenalin.