The effect of cyclosporine and liver autotransplantation on bile flow and composition in dogs.

Following liver transplantation bile formation may be influenced by hepatic denervation and cyclosporine therapy. To better establish any effect of liver transplantation on bile secretion, 6 mongrel dogs were studied: 3 underwent liver denervation by a modified autotransplantation procedure and insertion of a Thomas cannula to create a chronic duodenal fistula; 3 others had cholecystectomy and the duodenal cannula placement without manipulating the liver. One month after surgery, two control studies were done, one week apart. Then oral cyclosporine was given in doses of 5, 15, and 50 mg/kg/day for consecutive 1-week periods each. Twice on each cyclosporine regimen, after 4 and 7 days of therapy, the common duct was cannulated and bile collected for 5 h; animals were awake and fasted. The first 3 h of bile collection established basal conditions; flow was then stimulated with consecutive hour-long taurocholate infusions at 1 and 2 mumol/kg/min. In all dogs, bile flow increased as the cyclosporine dose increased, under both basal and bile salt-stimulated conditions. The increased flow primarily resulted from increased bile salt-independent flow. Cyclosporine had no effect on bile salt, bilirubin, or cholesterol secretion. Phospholipid secretion, however, decreased significantly in a dose-related manner with increasing cyclosporine in the dogs with autotransplanted livers, but not in the nontransplanted dogs. This decrease in phospholipid secretion resulted in a significant increase in the calculated cholesterol saturation of bile. Thus, cyclosporine administered orally is not cholestatic but rather increases bile flow independent of any change in bile salt secretion. Cyclosporine reduced phospholipid secretion in autotransplanted dogs, possibly related to denervation of the liver. The resultant change in biliary composition may pose a risk factor for gallstone formation.