Abstract: Objective To investigate the protective effects of mast cells on pancreas of rats with severe acute pancreatitis(SAP).Methods Ketotifen was injected intraperitonealey 30 min before or after SAP model, 3 h and 6 h after operation, pancreas was removed to make pathologic score, to count the number of MC by the method of toluidine blue staining and immunohistochemistry, to measure the MPO activation, the activation level of tryptase by western blot, and compared with those of SAP rats without ketotifen treatment.Results Pretreatment or early using of ketotifen after SAP can decrease the damage of pancreas, decrease the MC number and the level of MPO and tryptase.Conclusion MCs are activated in the early stage of SAP,and induce damage to pancreas. Pretreatment with or early using of ketotifen can decrease the severity of pancreas damage in SAP.

Key words: severe acute pancreatitis, mast cell, ketotifen