Abstract
The present study describes a novel technique for investigations of the enterohepatic circulation in the hamster with an extracorporeal bile duct that allows long-term bile collection in the free-moving animal. The animals recovered for 7 days after the operation before the external loop was cut and bile was collected over a period of 78 h. Under these optimal conditions, initial bile flow (651 +/- 89 microliters per 100 g.h-1) and the secretion rates of biliary lipids were several-fold higher than reported in an earlier study using the acute fistula hamster. Biliary cholesterol secretion amounted to 369 +/- 32 nmol per 100 g.h-1, phospholipid secretion was 2.6 +/- 0.3 mumol per 100 g.h-1, and total bile acid secretion was 31.9 +/- 2.2 mumol per 100 g.h-1. A clearcut diurnal rhythm was demonstrated for bile flow and all biliary constituents. After 9 h the depletion of the bile acid pool was complete and cholic acid synthesis derepressed 1.4-fold from a basal rate of 818 nmol per 100 g.h-1, whereas the derepression of chenodeoxycholic acid synthesis was even less pronounced. Biliary cholesterol output increased 2.2-fold, but the phospholipid secretion was constant during the full experiment. It may be concluded that the technique of an extracorporeal bile duct in the free-moving animal allows studies of bile secretion under optimal conditions. Most likely the bile secretion rates given above approach the physiological rates in the hamster.
Highlights
The present study describes a novel technique for investigations of the enterohepatic circulation in the hamster with an extracorporeal bile duct that allows long-term bile collection in the free-moving animal
In recent studies from this laboratory on the regulation of bile acid synthesis in the rat fitted with an extracorporeal bile duct (EBD) (Z), the sensitivity of the hepatic feedback inhibition was much less than originally observed in the acute bile fistula animal [15]
Recent improvements of the techniques applied to study the enterohepatic circulation in rat and other species have considerably enhanced the understanding of biliary physiology
Summary
The present study describes a novel technique for investigations of the enterohepatic circulation in the hamster with an extracorporeal bile duct that allows long-term bile collection in the free-moving animal. The animals recovered for 7 days after the operation before the external loop was cut and bile was collected over a period of 78 h Under these optimal conditions, initial bile flow (651 + 89 pl per 100 g e h-1) and the secretion rates of biliary lipids were several-fold higher than reported in an earlier study using the acute fistula hamster. Until recently most of the studies were undertaken using the rat fitted with an acute bile fistula [8,9,10] It could be demonstrated in the rat that after an appropriate recovery period with an extracorporeal bile duct, the rate of bile acid secretion is many-fold higher than previously appreciated [2, 3]. As a consequence of the lower capacity of hepatic cholesterol synthesis, the hamster, unlike the rat, regulates LDL transport in response to dietary intake of cholesterol or saturated fatty acids [18], to variations in bile acid pool size [19, 20], or to bile acid administration [21, 22]
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