THE ROUTE OF ABSORPTION OF THE ACTIVE PRINCIPLES OF THE POSTERIOR HYPOPHYSIAL LOBE

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Abstract
A primary absorption of the active principles of the posterior lobe directly into the blood-stream, rather than by the classical transneural-cerebrospinal route, is developed by experimental work utilizing oxytocic and melanophore assays of the active substance in blood plasma and cerebrospinal fluid. Allergic reactions of the assay preparations to foreign proteins were practically eliminated by dialysis of the test fluids; methods are described in detail. Normal concentrations in the blood stream in various parts of the body (dog) are given in terms of international pituitary powder. Changes after hypophysectomy are followed, as well as after nearly complete physiological isolation of the third (supra-infundibular) cerebral ventricle. Attempted chemical isolation of the principles from the blood by utilizing the Abel procedure, were unsuccessful. The active substance is, however, carried in the blood plasma; average concentration in the mixed arterial and venous bloods of dogs, beeves, or men is about 250 u mgm./mil; it behaves as if it were at least 2 entities, is diminished by major infections and by starvation, and increased during anabolic processes. Criteria of complete hypophysectomy are considered, and some cogent evidence conflicting with a direct blood-stream absorption theory is impartially presented.