Novel mechanism of vasodilation in inflammatory bowel disease.
OBJECTIVE
Endothelium-dependent dilation to acetylcholine (Ach) is reduced in mucosal arterioles from patients with inflammatory bowel disease (IBD). The contributions of both nitric oxide (NO) and endothelial-derived hyperpolarizing factor (EDHF) are decreased. We hypothesized that the remaining dilation results from products of cyclooxygenase.


RESULTS
High-performance liquid chromatography (HPLC) was used to isolate eicosanoid vasodilator products and videomicroscopy was used to examine vasomotor responses in human mucosal arterioles from subjects with or without IBD undergoing bowel resection surgeries. In subjects without IBD, Ach constricted (-52%+/-10%) arterioles devoid of endothelium. Indomethacin (INDO) (cyclooxygenase inhibitor) had no effect. In contrast, Ach dose-dependently dilated both intact and endothelial denuded arterioles from patients with IBD. The dilation was converted to constriction by INDO (-54%+/-9%; P<0.05 versus non-IBD) or by BWA868C (PGD2 receptor antagonist). Only in arterioles from subjects with IBD did Ach produce an arachidonic acid metabolite that comigrated on HPLC with PG D2 (PGD2). Exogenous PGD2 dilated (max=66%+/-4%) IBD arterioles.


CONCLUSIONS
In arterioles from IBD patients, Ach-mediated dilation shifts from endothelial production of NO and EDHF to nonendothelial generation of a PG, likely PGD2. This is a novel dilator mechanism arising from nonendothelial vascular tissue that compensates for loss of endothelium-dependent dilation. PGD2 appears to be important in regulating mucosal blood flow in patients with IBD, implicating potentially detrimental effects from nonsteroidal antiinflammatory drugs.
Hatoum
Ossama A
OA
Department of Medicine, Zablocki VA Medical Center, Medical College of Wisconsin, Milwaukee, WI, USA.
Gauthier
Kathryn M
KM
Binion
David G
DG
Miura
Hiroto
H
Telford
Gordon
G
Otterson
Mary F
MF
Campbell
William B
WB
Gutterman
David D
DD
D000109:Acetylcholine / Q000494:pharmacology; D000328:Adult; D000368:Aged; D016718:Arachidonic Acid / Q000493:pharmacokinetics; D001160:Arterioles / Q000502:physiology*; D001685:Biological Factors / Q000378:metabolism; D002250:Carbon Radioisotopes; D016861:Cyclooxygenase Inhibitors / Q000494:pharmacology; D004730:Endothelium, Vascular / Q000378:metabolism; D005260:Female; D006801:Humans; D066298:In Vitro Techniques; D007213:Indomethacin / Q000494:pharmacology; D015212:Inflammatory Bowel Diseases / Q000378:metabolism* / Q000503:physiopathology*; D008297:Male; D018715:Microscopy, Video; D008875:Middle Aged; D009569:Nitric Oxide / Q000378:metabolism; D015230:Prostaglandin D2 / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D011971:Receptors, Immunologic / Q000037:antagonists & inhibitors / Q000378:metabolism; D011982:Receptors, Prostaglandin / Q000037:antagonists & inhibitors / Q000378:metabolism; D014664:Vasodilation / Q000187:drug effects / Q000502:physiology*; D014665:Vasodilator Agents / Q000494:pharmacology
D001685:Biological Factors; D002250:Carbon Radioisotopes; D016861:Cyclooxygenase Inhibitors; D017382:Reactive Oxygen Species; D011971:Receptors, Immunologic; D011982:Receptors, Prostaglandin; D014665:Vasodilator Agents; C067410:endothelium-dependent hyperpolarization factor; D016718:Arachidonic Acid; D009569:Nitric Oxide; D000109:Acetylcholine; D015230:Prostaglandin D2; D007213:Indomethacin; C036293:prostaglandin D2 receptor