Tin-protoporphyrin inhibits carbon monoxide production in adult male Wistar rats with common bile duct ligation.

The excretion rate of CO (VeCO), an index of total bilirubin production, and the total plasma bilirubin level are significantly elevated by 72 h after ligation of the common bile duct in adult male Wistar rats. At 72 and 96 h, rats prepared in this manner were subcutaneously injected with 50 mumol/kg body weight of tin-protoporphyrin IX (TP) (n = 5) or saline (n = 6). At 120 h after surgery, the VeCO had fallen from the pretreatment level in the TP-treated animals by 22% (P less than 0.025) compared with no significant change in the saline-treated controls. The plasma total bilirubin level of the experimental animals had also declined by 32% (p less than 0.0005) compared with their pretreatment level. The hyperbilirubinemia of the saline-treated controls was not significantly modified. These results suggest that TP reduces bilirubin production and plasma total bilirubin levels in adult rats with surgically created obstructive jaundice.