By actively changing the pH of the enema solution of calcium preparations, especially of calcium chloride, the influences of the varying pH of the enema solution on the absorption of calcium in the large intentine was investigated in the first place.
When the reaction of the enema was shifted to the alkaline side with NaOH, the absorption of calcium chloride in the large intestine was evidently enhanced at pH 8.0. At pH 7.0 or pH 9.0, the absorption remained the same as in the control tests with the solution without adjustment of pH, and there was no enhancement of absorption note-d
When the reaction of the enema was shifted to the acid side with acetic acid, lactic acid or hydrochloric acid, the absorption of calcium chloride in the large intestine was remarkably enhanced at pH 2.8 in all cases. Especially, when the reaction was adjusted with hydrochloric acid, the absorption was most distinctly enhanced, and all the rabbits used demonstrated intoxication symptoms and became fatal. As already reported by Hitomoto and Kato, the calcium content in the peritoneal fluid in such cases was found extremely increased.
Previously, Kato reported a very interesting result that when calcium preparations combined with the mixture of glycocoll and glucose is administered as enema, the absorption of calcium chloride in the large intestine is greatly enhanced, and further, that calcium lactate and calcium sulfate, which are usually not absorbed from the large intestine, are
also absorbed. Whereas, I confirmed that, when calcium sulfate solution is acidified to pH 2.8 with acetic acid, calcium sulfate is absorbed in the large intestine, though slower compared with calcium chloride, and the serum calcium content is somewhere about 24mg/dl even after 210 minutes. Adjustment of the reaction to pH 2.8-3.0 combined with ox bile does not particularly enhance the absorption compared with the above results, but when too much ox bile is combined, intoxication death caused by abnormal absorption of biliary acid and excess of calcium content in the serum is observed.
In the case of oral administration, even doubled amount of calcium chloride solution of the case of enema (20cc. per kg. of 5% calcium chloride solution) generally increase the serum calcium content only slightly. Whereas, when ox bile is combined, the serum calcium content increases rapidly indicating the enhanced absorption of calcium in the small intestine. Differing from the case of enema, in the case of oral application, no particular enhancement of the absorption of calcium is observed even the reaction of calcium chloride solution is adjusted to pH 2.8 with acetic acid, lactic acid or hydrochloric acid. Further, when ox bile is combined with calcium chloride solution with adjusted pH, no particular difference is noted in the influence of bile from that in the case combined with the same solution without pH adjustment. Despite the fact that the absorption of calcium in the small intestine does not demonstrate any difference between that of calcium solution with adjusted pH or without pH adjustment combined with ox bile, the absorption of calcium administered in combination with ox bile induces much more rapid and distinct enhancement of calcium absorption compared with that of the application of calcium alone. Consequently, it became essential to know calcium absorption in the stomach. When calcium chloride solution was orally administered after the pylorus of stomach was ligatured, the fact, that the serum calcium content did not increase during the elapse of 210 minutes from the administration even in the combined application with ox bile, was confirmed. By the above fact, it is presumed that the rapid increase in serum calcium content in the case of combined application with ox bile may be induced by rapid transfer of calcium chloride solution from the stomach to the small intestine and enhancement of calcium absorption in the small intestine by ox bile.
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