STUDIES ON THE SECRETION OF BILE

Abstract

The effect of various procedures on the composition of bile was studied in a number of biliary fistula dogs, the minimal number used for each procedure being three. The following observations were made: Under standard conditions of feeding with or without the return of bile to the duodenum, the vol. and cholic acid output did not deviate more than [plus or minus] 8% from the mean daily values; the cholesterol and total pigment output was subject to [plus or minus] 20% deviation. When the Rous-McMaster method was used, which did not employ suction to overcome the resistance to the flow of bile caused by the drainage tubes, etc., the vol. output was less and was subject to greater variation. The same was true of cholic acid output, but significant results might be obtained by their method in so far as the output of the various principle biliary constituents were concerned. When an animal was fed 3 times daily without the return of bile, the output of cholates, cholesterol and pigment was quite constant for 3 periods. When bile is returned after each meal, the % increase in vol., cholesterol and pigment output was essentially the same, but the output of cholates was markedly increased. The cholic acid secreted daily by the dogs (8 to 15 kg. in wt.) when receiving the diet alone ranged from 12 to 1.6 g.; when all the bile was returned to the duodenum from 6.5 to 9.0 g. were secreted. From 10 to 15% of the cholic acid disappears during the enterohepatic circuit. Thus if from 7-9 g. of cholic acid traversed the enterohepatic circuit 3 times each day, the total loss would compensate for that formed endogenously and from the diet, and a more or less constant output of cholic acid would be maintained. When bile was returned, the output of cholesterol was increased and from 33 to 66% of the cholesterol introduced in the bile appeared to be absorbed and excreted. Bile salts, containing no cholesterol, administered orally or intraven. increased cholesterol output. Thus a relation between vol. and cholesterol output exists, although the relation is not a strict one. When bile salts, containing no pigment, were given orally the output of pigment was not significantly increased. However when bile was returned to the intestine, it appeared that about 30% of the pigment was in some way absorbed and re-excreted by the liver. The subcut. adm. of 1 mg. of atropine and of 2.7 mg. of p methyl acetylcholine, the latter being given in divided doses every 20 mins. for 3 hrs., prevented the usual increase in vol. and the cholic acid content of the bile that occurred after a meal.