A day to day study has been made of the calcium content of the total liver bile of dogs intubated under sterile conditions. The concentration of this element in the bile is fairly constant under physiological conditions which do not involve wide fluctuations in the secretory output. It follows that the calcium yield for each 24 hour period in general varies directly with the amount of the bile. But when this amount becomes greatly lessened, as the result of fasting, the concentration of calcium becomes markedly increased, though not sufficiently so to compensate for the lessened volume. When the bile amount rises much above the average after the ingestion of food in quantity, the calcium content, unlike that of pigment, does not become correspondingly diminished, but tends to remain the same as ordinarily. Hence when great amounts of bile are put out, so too are relatively great amounts of calcium. This is not because of the increased ingestion of the element. For neither feedings with bone meal, nor the administration of large quantities of calcium salts intravenously or by mouth has any effect to alter the biliary output of calcium.
The normal gall bladder, far from secreting calcium into the bile, as some have supposed, acts to remove this element from the secretion, and removes carbon dioxide as well.
The "white bile," which is a specific secretion of the bile ducts, contains but little calcium, like the mucous secretions from elsewhere in the body. The concentration is only slightly greater than that in the blood plasma, and contrasts significantly with the high concentration to be noted in true bile of the fasting animal. Evidently the greater portion of the bile calcium must be secreted, not by the duct walls, but by the liver itself.
The findings have an evident bearing on the problem of cholelithiasis.