The effects of 5-HT blockade in graded intestinal vascular obstruction in the rat

Intestinal vascular obstruction with an obstruction pressure of 120 cm of water for one hour induces a 75% mortality in rats. The mortality is associated with intestinal mucosal lesions, release of cardiotoxic material to the intestinal venous blood and trapping of platelets in the lungs. The present series of experiments was performed to study the role of released serotonin in the pathogenesis of the circulatory collapse that follows in this shock model. This was done by pretreating rats subjected to standardized intestinal vascular obstruction with Ketanserin, a selective 5-HT2 receptor blocking agent. It was found that Ketanserin reduced the increase in hematocrit otherwise induced but had no significant effect on mortality, trapping of platelets or the intestinal mucosal lesions. It is concluded that serotonin is probably not of significant importance in the pathogenesis of the circulatory collapse following intestinal vascular obstruction.