ウシとヒヅジに皮下注射された Progesterone の末梢血中の運命について

Studies were made to explore the retention, metabolic products, and rate of progesterone in the peripheral blood of cow and ewe following subcutaneous injection of progesterone. In them, these cows and an ewe were ovariectomized and used. Two gram of non-labelled progesterone and 50 μCi (286 μg) of ¹⁴C-progesterone were combined and suspended in oil. The resultant suspension was injected subcutaneously to two cows. In them, the radioactivity in the blood showed an increase until the 4th hour following injection, then a rapid decrease to the 9th and 12th hour, and a more gradual decline to the 24th and 36th hour, respectively. There was a considerable difference in the blood level of the injected progesterone between the two cows. One cow showed a level almost twice or more as high as that shown by the other. The cause for such difference was not known but it was assumed that there might be a difference in absorption of progesterone from the site of injection, the ability of the liver to eliminate the hormone or uptake of the hormone by fat tissue between these cows. Determination by a gas liquid chromatography indicated the presence of 1.15 and 1.77 μg of progesterone per 100 ml of plasma in cows 496 and 602, respectively. A total of 0.38 μg per 100 ml of 20β-o1 was isolated from a combined sample of plasma collected from the two cows. A sample collected from each cow appeared to contain a few metabolites which were too little to be determined by the method employed. The third cow (No. 202) was injected subcutaneously with 75 μCi (ca. 500 μg) of ¹⁴C-progesterone, and 600 ml of blood plasma was with drawn from it at the 4 th hour post injection. The plasma sample was subjected to column chromatography, solvent partition, and finally thin layer chromatography for the separation of progesterone and the metabolites, if any. Only progesterone and 20β-o1 were noted apparently to be present. A few other metabolites also appeared to be contained in the sample, but they were too little to be determined by the method used. In the two cows injected with about 2 g of progesterone, the recovery of progesterone in the venous blood was approximately 1/1, 000, 000 to 1/2, 000, 000 per 100 ml of plasma. It was, however, about 1/200, 000 of the injected hormone recovered, when a very small does was given by the subcutaneous route to a cow. This difference in recovery rate in the venous blood amounting to 5 to 10 times may have been induced by the difference in size of dose used. There was also a small difference in the ratio of progesterone to 20β-o1 in the blood, when these different doses had been given. This ratio was approximately 100:13 and 100:10 (or less than 10), at the 4th hour following injection. To an ovariectomized ewe, 20 μCi of ¹⁴C-progesterone was injected subcutaneously. Progesterone and 20α-o1 seemed to be present in a sample collected from the ewe at the 3rd hour, but no other metabolites could be picked up by the TLC separartion. The ratio of progesterone and 20α-o1 was approximately 100:5.