Expression of inducible nitric oxide synthase in the lower esophageal sphincter of the endotoxemic opossum.
BACKGROUND
Endotoxin modulates esophageal motor function by increasing nitric oxide (NO) production. The aims of this study were to examine inducible nitric oxide synthase (iNOS) induction in the lower esophageal sphincter (LES) of endotoxemic opossums and to investigate the effects of aminoguanidine (AG), a selective inhibitor of iNOS, on plasma nitrite/nitrate levels and on iNOS protein and mRNA expression after exposure to lipopolysaccharide (LPS).


METHODS
Before and 12 h after the intravenous administration of LPS and/or AG, plasma nitrite/nitrate levels were determined. The iNOS protein and mRNA expression were investigated in the tissues taken from the LES by Western blot and reverse-transcriptase polymerase chain reaction (RT-PCR).


RESULTS
Plasma nitrite/nitrate levels were significantly increased by LPS. The increase in plasma nitrite/nitrate produced by LPS was significantly decreased by AG. Western blot and RT-PCR demonstrated that iNOS expression was markedly increased by LPS, and attenuated slightly by AG.


CONCLUSIONS
These studies support the hypothesis that endotoxin increases NO production by the induction of iNOS protein and mRNA.
Park
Hyojin
H
Department of Internal Medicine, University of Iowa College of Medicine and VA Medical Center, Iowa City, USA.
Clark
Eugene
E
Cullen
Joseph J
JJ
Koland
John G
JG
Kim
Myong Soo
MS
Conklin
Jeffrey L
JL
D000818:Animals; D001483:Base Sequence; D015153:Blotting, Western; D004195:Disease Models, Animal; D019446:Endotoxemia / Q000201:enzymology* / Q000503:physiopathology*; D004943:Esophagogastric Junction / Q000187:drug effects* / Q000503:physiopathology*; D005260:Female; D005786:Gene Expression Regulation; D006146:Guanidines / Q000494:pharmacology*; D008070:Lipopolysaccharides; D008297:Male; D008969:Molecular Sequence Data; D009569:Nitric Oxide / Q000032:analysis / Q000378:metabolism; D019001:Nitric Oxide Synthase / Q000235:genetics / Q000378:metabolism*; D052247:Nitric Oxide Synthase Type II; D009893:Opossums; D011336:Probability; D012333:RNA, Messenger / Q000032:analysis; D011897:Random Allocation; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012680:Sensitivity and Specificity; D018709:Statistics, Nonparametric
D006146:Guanidines; D008070:Lipopolysaccharides; D012333:RNA, Messenger; D009569:Nitric Oxide; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II