Haemodynamic effects of phenoxybenzamine and dopamine in segmental ischaemia of the rat small intestine.

Two groups of rats were subjected to a segmental intestinal ischaemia of a degree which, according to earlier investigations with this experimental model, causes secondary impairment of the splanchnic blood flow. Both groups were given plasma and an alpha-adrenergic blocking agent (phenoxybenzamine). They were also given dopamine but in different doses, 12 and 50 micrograms X min-1 X kg-1 b.w., respectively. It was found previously that a normal blood flow in the non-occluded parts of the small intestine could be maintained by phenoxybenzamine or the lower dose of dopamine alone in combination with plasma, but the higher dopamine dose caused vasoconstriction, probably because of an alpha-stimulating effect. The combined treatment with penoxybenzamine and dopamine in the present experiments normalized the intestinal blood flow in the non-occluded parts in both groups, i.e. also in the group treated with the higher dose of dopamine. Moreover, the pancreatic circulation was normalized in both groups. Hence alpha-adrenergic blockade combined with dopamine and plasma administration seems to have a positive effect on the splanchnic circulation during segmental intestinal ischaemia in the rat.