Effect of cyproheptadine on endotoxin-induced pulmonary platelet trapping.

The adult respiratory distress syndrome (ARDS) seen in endotoxin shock is accompanied by the release of beta-endorphin. The hypotension that is seen in endotoxin shock can also be produced by injection of beta-endorphin and is effectively blocked by the use of antiserotonin drugs. Serotonin injection in dogs causes lung changes similar to those seen in endotoxin shock. Pulmonary platelet trapping (PPT) is one of the factors in the evolution of ARDS. The effects of cyproheptadine, an antiserotonin drug, were evaluated on PPT in dogs injected with endotoxin. Dogs treated with cyproheptadine both prior to and after induction of endotoxin shock were compared with the standard endotoxin shock model. Blood pressure, platelet aggregability, and wet/dry lung weight ratio were studied in all groups. Posttreatment with cyproheptadine obviated PPT indicating the applicability of cyproheptadine in the treatment of ARDS. Pretreated dogs had PPT not significantly different from endotoxin controls, suggesting that blocking of serotonin before shock activates other vasoactive substances, which may include prostaglandins or prostaglandin derivates.