Reduced vascular sensitivity to norepinephrine in portal-hypertensive rats.
The development of portal hypertension following chronic portal vein stenosis is accompanied by a significant increase in intestinal blood flow. The present study was designed to determine whether intestinal vascular sensitivity to norepinephrine (NE) is also affected by chronic portal vein stenosis. Using a blood-perfused, in situ rat small intestine preparation, we found that, when compared with control animals, a significantly greater molar concentration of NE was required to achieve the same proportional increase in intestinal vascular resistance in portal-hypertensive animals. The mean ED50 value (+/-SE) for the portal-hypertensive group (704.3 +/- 186.1 nM) was significantly greater (P less than 0.05) than the mean ED50 value for the control group (271.4 + 48.1 nM). This finding implies that sympathetic maintenance of intestinal vascular tone may be impaired following chronic portal vein stenosis, possibly accounting for part of the intestinal hyperemia associated with portal hypertension.
D000818:Animals; D001808:Blood Vessels / Q000187:drug effects; D002908:Chronic Disease; D004305:Dose-Response Relationship, Drug; D004351:Drug Resistance; D006439:Hemodynamics; D006975:Hypertension, Portal / Q000503:physiopathology*; D007421:Intestine, Small / Q000098:blood supply*; D008297:Male; D009638:Norepinephrine / Q000494:pharmacology*; D011312:Pressure; D051381:Rats; D011919:Rats, Inbred Strains; D013154:Spleen / Q000503:physiopathology; D014655:Vascular Resistance / Q000187:drug effects; D014690:Venous Pressure
D009638:Norepinephrine