Effects of phenobarbitone and 6-methylprednisolone pretreatment on pressure/flow relations in the superior mesenteric and iliac arterial beds of the rat.

The in-situ blood perfused rat superior mesenteric arterial and right iliac arterial preparations were used to investigate the effects of pretreatment for 5 days with either phenobarbitone (80 mg kg-1 daily) or 6-methylprednisolone (17 mg kg-1 daily) on regional vascular resistances. The elevation of the regression of perfusion pressure on perfusion rate in the superior mesenteric arterial bed was significantly decreased by both phenobarbitone and 6-methylprednisolone over the range of flow rates used. Neither phenobarbitone nor 6-methylprednisolone had a significant effect on hepatic portal venous pressure nor was there any significant effect on the regression of perfusion pressure on flow rate in the in-situ iliac arterial bed. It is concluded that pretreatment with either phenobarbitone or 6-methylprednisolone lowers vascular resistance in the superior mesenteric arterial by approximately 9 and 8% respectively but does not affect vascular resistance in the iliac arterial bed.