Heme oxygenases (HOs) convert protoheme to biliverdin, which in turn is enzymatically metabolized to bilirubin . Tin mesoporphyrin IX is a potent, competitive inhibitor of HO activity in vitro (Ki = 14 nM). It inhibits hepatic, renal, and splenic HO activity in vivo for extended periods of time. Tin mesoporphyrin IX blocks bilirubin production in vivo, decreasing HO activity in animal models of hyperbilirubinemia. Tin mesoporphyrin IX can be used to study the physiological roles of induced HO-1 expression in animal models.
