The development of a method for the collection of total bile from dogs in a sterile state and uninfluenced by the gall bladder, day after day for weeks, has rendered possible an accurate study of the influence of diet upon the cholesterol output of the secretion.
When a diet rich in cholesterol is given the amount of the substance in the bile greatly increases. Not only this but the concentration per cc. is, in almost every instance, greater. An increase in the total food intake, by the addition to the ordinary ration of a bone mash diet containing only a slight additional amount of cholesterol (200 mg.) produces a similar, though lesser, increase. In the fasting dog, the cholesterol yield is greatly cut down.
The increase in the cholesterol after food rich in the substance does not depend on the cholagogue action of this latter, though it is true that the concentration of cholesterol in the bile usually increases with the bile volume.
Though fasting cuts down the cholesterol of bile, the concentration of the substance per cc. is greatly increased. On an ordinary diet the yield of it fluctuates abruptly and considerably from day to day. In general the rule holds that an animal eating largely puts out not only much more bile but much more cholesterol. The relation between bile quantity and cholesterol yield is anything but a fixed one, however.
The cholesterol yield of the bile does not parallel that of bilirubin. The pigment output from day to day remains relatively constant as compared with that of cholesterol.