Effects of cyproheptadine on plasma superoxide dismutase activity and malondialdehyde content in rabbits with hemorrhagic shock.

Profound hemorrhagic shock was produced in thirty rabbits by exsanguination via the carotid artery until blood pressure (BP) reached 5.3 kPa (40 mmHg) and was sustained for a period of 90 minutes. The rabbits were equally divided into cyproheptadine (Cyp) treated group and control group. Blood samples 30 minutes after liquid and blood infusion and administration of Cyp (10 mg/kg) were collected from the carotid artery, and the plasma superoxide dismutase (SOD) activity and malondialdehyde (MDA) content measured. The results showed that Cyp remarkably enhanced the plasma SOD activity (2462 +/- 338 vs 1955 +/- 596, P < 0.01) and reduced MDA content (2.68 +/- 0.24 vs 3.20 +/- 0.49, P < 0.01). We believe that the increase of O2 production plays an important role in the development of shock, the single blood and liquid infusion can not significantly improve the shock conditions. Scavenging oxygen free radicals and alleviating cellular damage and multiple organ failure are the possible mechanisms of cyproheptadine anti-shock effect.