| Abstrakt: |
Data defining bile salt pool sizes and composition during the development of cholesterol gallstones may clarify our understanding of the etiology of cholelithiasis. Bile salt pool size reduction is common among patients with gallstones (1, 2) and in populations predisposed to gallstones (3). Sequential measurements of bile salt pool size in an appropriate animal gallstone model should establish the sequence of events during the formation of gallstones, and the interrelationship of bile salt pool size to those events. Our finding that the prairie dog is an excellent model for the study of cholelithiasis (4, 5) has been confirmed by other investigators (6). Studies to clarify the relationship of the bile salt pool to gallstone formation in this model require a reliable technique for determining the effect of various perturbations on bile salt pool size and synthesis rates. The studies reported herein compare two methods for estimating pool sizes in small animals.Acute experiments in the rat have relied on the “washing out” of the bile salt pool (7, 8), without confirmation that the bile salt pool measured accurately estimates the recirculating pool. Studies in humans using the isotope-dilution techniques (9) rely heavily on equilibration between the gallbladder subpool and recirculating pool. This assumption is especially important in the recently reported “one-sample” determinations of bile salt pool size (10). Since the prairie dog has a gallbladder, a “one-point” measurement of bile acid pool size might be unreliable if equilibration of the gallbladder and recirculating pool were incomplete. We, therefore, compared a modified isotope-dilution technique with the wash-out technique used on animals lacking gallbladders.Methods.Two groups of adult (800- to 1000-g) prairie dogs were studied. One group was fed a control trace-cholesterol laboratory chow, the second was fed chole-lithogenic chow (0.48 g of cholesterol/100 g) for 10 days. |
