title: Vascular endothelium contributes to decreased aortic contractility in experimental sepsis.
abstract: In this study, we compared responses to norepinephrine (NE) by thoracic aortic rings isolated from rats made septic by cecal ligation with puncture, and aortic tissue from sham-operated control rats. We also examined the responses of septic and sham-operated rat aortas after removal of the vascular endothelium. Acetylcholine caused relaxation of NE-induced contractions in septic and sham tissue with an intact endothelium but had no effect on tissue with the endothelium removed experimentally. In preparations with intact endothelium, septic tissue manifests a significantly diminished maximal contractile response to NE (424 +/- 62 (SE) mg tension/mg tissue) in comparison to sham tissue (747 + 30). Tissues with the endothelium removed show no significant maximal contractile difference between septic (688 +/- 23) and sham (669 +/- 32) preparations, or the equivalent sham tissue with an intact endothelium. No difference in the log ED50 for sham tissue (-7.33 +/- 0.12 M) and septic tissue (-7.53 +/- 0.15) with intact endothelium existed. Removal of the endothelium from both septic and sham tissue shifted the dose response curves to the left, disclosing a significant difference in the ED50 between sham (-8.88 +/- 0.14) and septic (-8.18 +/- 0.20) tissue. In conclusion, a significant impairment of vascular contractility in response to NE, with no change in ED50, persists in septic vascular tissue in vitro, and the sepsis-induced defect in contractility is mediated, at least in part, by vascular endothelium, since removal of the endothelium partially restores the NE-stimulated contraction to normal.
mesh_terms: D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D001013:Aorta, Thoracic / Q000187:drug effects / Q000503:physiopathology; D002432:Cecum; D004727:Endothelium / Q000502:physiology; D008026:Ligation; D008297:Male; D009638:Norepinephrine / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D012772:Shock, Septic / Q000503:physiopathology*; D014661:Vasoconstriction / Q000187:drug effects*
chemical_list: D000109:Acetylcholine; D009638:Norepinephrine