SURVIVAL IN THE CIRCULATION OF THE GROWTH AND ADRENOCORTICOTROPHIC HORMONES AS EVIDENCED BY PARABIOSIS

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Abstract
Rate of exchange of blood between the members of a parabiotic pair was detd. with erythrocytes labeled with Fe59. The flow rate, 0.66% of the blood volume per minute, was found to be remarkably constant for all pairs and under varying conditions. Distribution of a hormone in the fluid spaces of the body might be called a measurement of the "hormone space" of the body and was judged by the extent of dilution of an intravenously admd. hormone in plasma and lymph. Both growth hormone and adrenocorticotropic hormone were found to leave the blood vascular channels and become distributed in the larger volumes of the extra-cellular fluid of the body. Distr. of growth hormone and ACTH between members of such pairs, was detd. either by leaving the pituitary intact in only one of the partners or by removing the pituitaries from both members and injecting the hormone into only one partner. The increase in anus-tail-tip length or the resulting adrenal weights, when compared to standards, served as quantitative measurements of the amount of hormone received by each parabiont. These studies enable one to calculate the avg. life of these hormones in the circulation of the rat. The avg. life of growth hormone was found to be 544 minutes. The avg. life of ACTH was found to be 17 minutes.