On the Relationship of Gall-Bladder Emptying to Ingested Fats

Abstract

AS the result of a series of experiments made on cats the fact was first pointed out by Boyden (1), at the Boston meeting of the American Association for the Advancement of Science, in 1922, that the ingestion of a mixture of egg yolk and cream caused a rapid expulsion of bile from the gall bladder. On the publication by Graham and Cole (2) of their method for the visualization of the human gall bladder, Silverman and Menville (3) at once applied this technic to a study of gall-bladder emptying by the intraduodenal instillation of magnesium sulphate solution. The results showed that the gall bladder emptied when repeated injections of this chemical were made into the duodenum. Subsequently, Boyden (4) made a study of the problem and was able to show by experiments made on himself that in the human subject the administration of the yolk of four raw eggs and a half-pint of cream caused a rapid expulsion of bile, a phenomenon which was not noted when lean meat or carbohydrate was eaten. The experiments of Boyden led him to believe that the egg yolk was more efficient in causing expulsion of bile than the cream, and he therefore carried out experiments with cats in which substances containing preponderating amounts of the three lipoids known to occur in the egg yolk (neutral fat, lecithin, and cholesterol) were present. For this purpose he used lard, lecithin (Merck), and lanolin, each of these substances being fed to the animals by means of a stomach tube, both with and without cream. The results obtained indicated that lecithin was most active. In a later series of experiments (5), however, with samples of lecithin as prepared by Eastman and used in the Harvard laboratories, it was found that the administration of this substance failed to cause complete emptying of the gall bladder. This finding has caused Boyden to discard the theory that this body is the specific substance responsible for the effect of egg yolk. The initial findings of Boyden have received corroboration at the hands of numerous investigators, an excellent discussion of whose work is to be found in the recent paper of Hamrick (6). It therefore need not be discussed here. As regards the mechanism of the stimulation of the gall bladder by ingested egg yolk, the question arises not only as to what constituent of this food is the active principle but also as to how it effects the desired result, whether by a hormonal type of action due to the absorption of some constituent or product of digestion into the blood stream, or due to the presence in the duodenum of the egg yolk itself or some digestion product produced therefrom. In his latest work Boyden (5) states that his experimental results “indicate that the gall-bladder musculature does not respond to the presence of food in the gastro-intestinal tract unless digestion and absorption have occurred,” and that “the gall bladder is subject to both nerve and hormone control.”