1254 THE EARLY-ONSET EFFECT OF BILIARY OBSTRUCTION ON CO EXCRETION IN THE RAT

Common bile duct ligation in the adult male Wistar rat increases the rate of total bilirubin formation (TBF) as estimated by the excretion of carbon monoxide (VeCO). This increase is not due to elevation in the hepatic subcomponent of “earlylabeled” bilirubin (ELB) formation as measured by 14C-4-Δ-aminolevulinic (J Pediatr Gastroenterol Nutr 3:790, 1984). This study examines total ELB formation in rats 3 days after complete common bile duct ligation. VeCO was measured preoperatively and on the third day after creation of complete biliary obstruction. The rate of ELB formation was measured by recovery of exhaled 14CO following intraperitoneal injection of 14C-2-glycine (20 μCi/100gm) on the third postoperative day. Preoperatively, there was no significant difference in the VeCO between control and experimental rats. On the third postoperative day, the VeCO of control rats had returned to baseline from an elevated rate, due to the surgery, while the VeCO of experimental rats was increased by 31% (paired t-test, p<0.02). Total fractional recovery of injected label over a 36 hr collection period was similar for control (8.5±0.7 × 10−5, n=8) and experimental (8.2±0.2 ± 10−5, n=7) rats. Based on these data, we conclude that the rise in TBF in this obstructive model is not due to ELB formation. The results further suggest that increased red cell destruction occurs rapidly after short-term biliary obstruction, and may cause the increased TBF, contributing to the pathogenesis of obstructive jaundice.