PHYSIOLOGICAL CHANGES OCCURRING IN THE BLOOD OF THE PACIFIC SALMON (ONCORHYNCHUS TSHAWYTSCHA) ACCOMPANYING SEXUAL MATURATION AND SPAWNING1

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Abstract
A study was made of thechanges occurring in a number of blood constituents during the spawning migration of the Pacific salmon (O. tshawytscha). The glucose content of the blood increased to about twice that found in salmon in the sea. Rarely wasglucose found in the urine. Theconcentrations of sodium and potassium decreased, the latter to a marked degree. Cholesterol values rose during the migratory period, then fell at the time of spawning to concentrations lower than those found in seasalmon. Total proteins exhibited a pronounced diminution. Protein-bound iodine decreased progressively from the seato thespawning grounds. Estimations of thenumber of redblood cells, hemoglobin content and packed cell volume showed fluctuations during the migration period butbythetime of spawning the blood picture was in general like that of the sea salmon. Accompanying the above changes was a progressive rise in the concentration of 17-hydroxycorticosteroids to high levels at thetime of spawning. Detailed comparison with the characteristic physiological and histological features of Cushing’s syndrome revealed many similarities between thespawning salmon and the human patient suffering from Cushing’s syndrome.