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

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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.

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