DIFFERENCE IN ACTION ON HEART BEAT COMPARED WITH THAT ON METABOLISM OF NORMAL AND TOXIC GOITER THYROIDS

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Abstract
Fresh human and pig thyroids were fed to thyroidectomized rats for comparison of effects on heart rate and metabolism. Pig''s gland showed either slight or moderate stimulating effect on heart rate as compared with the simultaneous effect on rate of metabolism. Normal human glands had a slight action on the heart, whereas thyroids removed surgically from patients with toxic goiter, who had been treated with I, stimulated the heart rate to a variable but always quite marked degree, in some instances far greater than would be expected from the concomitant effect on metabolism. A single thyroid from a patient with toxic goiter, without pre-operative I medication, had a weaker action on heart rate. Subjecting the glands of weak cardiac action to autolysis did not alter the quality of physiologic activity. The tentative theory is presented that I medication tends to accumulate in the thyroid the factor responsible for stimulation of heart rate and that the marked action on the heart observed with commercial dried thyroid is caused either by its content in pathologic glandular material or by the excessive use of iodized salt in the feed of the animals which supplied the glands.