THE EFFECT OF ANTERIOR PITUITARY EXTRACT ON THE RESPONSE OF THE DENERVATED HEART TO ADRENINE

Abstract

The denervated heart underwent no noteworthy change of sensitivity to adrenine after the first days following section of its nerve supply. In 4 of 5 cats the administration of ant. pituitary extract (APE) for 1 to 2 weeks was accompanied by an increase in the sensitivity of the denervated heart to a standard dose of adrenine. This increase did not appear for 5-8 days after the extract began to be administered. In 2 of 4 cats whose metabolism was detd., there were 20% and 22% rises in the metabolic rate after APE. A marked increase in basal heart rate was also observed in the same 4 animals after APE. In 3 of the above animals the thyroid was removed. After this operation a 2d administration of APE caused no increase in the adrenine response. Similarly, in 3 other animals in which thyroidectomy was performed at the beginning of the expt. there was no increase in sensitivity to adrenine after APE. APE caused a slight increase in the basal heart rate of the thyroidectomized animals, but its effect was much less than when the thyroid was intact. After the administration of thyroid there was a marked increase in the adrenine response of the denervated heart in 5 animals. In these animals thyroid feeding also caused a considerable increase in the basal heart rate. Removal of the ant. lobe of the pituitary in one animal with the thyroid intact was followed by a decrease in the sensitivity of the denervated heart to adrenine.