LPS-induced muscularis macrophage nitric oxide suppresses rat jejunal circular muscle activity.
Cellular mechanisms of sepsis-induced ileus remain an enigma. The study aim was to determine the role of nitric oxide (NO) in mediating the suppression of rat jejunal circular smooth muscle activity during endotoxemia. Isolated muscularis inducible NO synthase (iNOS) mRNA was measured by RT-PCR, immunohistochemistry was employed to localize iNOS protein, and contractile activity was measured in an organ bath. The low basal expression of muscularis iNOS mRNA expression was increased in a time-dependent fashion after lipopolysaccharide (LPS), resulting in a 20-fold increase over controls 3 h after injection. Immunohistochemistry of muscularis whole mounts and dissociated muscularis cells for iNOS revealed staining only in the muscularis macrophages 12 h after LPS. LPS caused a 68% reduction in spontaneous muscle activity 12 h after injection, which improved by 53% after the in vitro application of the selective iNOS inhibitor L-N(6)-(1-iminoethyl)lysine. Similar results were obtained in C57BL/6 mice but not in iNOS knockout mice. These data demonstrate that macrophage iNOS plays an important role in mediating LPS-induced intestinal circular muscle suppression.
Eskandari
M K
MK
Division of Gastroenterology, Departments of Surgery and Medicine, University of Pittsburgh Medical School, Pittsburgh, Pennsylvania 15261, USA.
Kalff
J C
JC
Billiar
T R
TR
Lee
K K
KK
Bauer
A J
AJ
D000818:Animals; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005769:Gastrointestinal Motility / Q000187:drug effects / Q000502:physiology*; D007150:Immunohistochemistry; D007583:Jejunum / Q000187:drug effects / Q000502:physiology*; D008070:Lipopolysaccharides / Q000494:pharmacology*; D008264:Macrophages / Q000378:metabolism*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout / Q000235:genetics; D009130:Muscle, Smooth / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D009569:Nitric Oxide / Q000502:physiology*; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II; D019335:Nitroarginine / Q000494:pharmacology; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D011912:Rats, Inbred ACI
D004791:Enzyme Inhibitors; D008070:Lipopolysaccharides; D012333:RNA, Messenger; D019335:Nitroarginine; D009569:Nitric Oxide; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; C496317:Nos2 protein, mouse; C496318:Nos2 protein, rat