Effects of dopamine in segmental intestinal ischaemia studied with dopamine receptor blockers

The influence of dopamine blocking agents, namely pimozide 0.1 mg X kg-1 body weight (b.w.) and metoclopramide 3 mg X kg-1 b.w., on the effects of dopamine on central and regional haemodynamics was studied in rats. The metoclopramide dose was given twice during the experiments. An experimental model involving segmental ischaemia of the small intestine was used. According to earlier investigations administration of dopamine and plasma counteracts the negative haemodynamic effects of such ischaemia. In rats treated with pimozide this drug had some effects per se in the controls, slightly reducing cardiac output and the blood flow in the proximal half of the intestine. On the other hand, in the experimental group the positive effect of dopamine seemed to be unaffected by pimozide treatment. In rats treated with metoclopramide, dopamine did not improve the considerable decrease in intestinal and pancreatic circulation caused by the segmental ischaemia.