Attenuated nitric oxide synthase activity and protein expression accompany intestinal ischemia/reperfusion injury in rats.
Intestinal ischemia/reperfusion (I/R) leads to bowel impairment via the release of reactive oxygen species (ROS) and neutrophil infiltration. In addition to modulating intestinal integrity, nitric oxide (NO(*)) inhibits neutrophil activation and scavenges ROS. Attenuated endogenous NO(*) formation may result in the accrual of these deleterious stimuli. Therefore, we determined nitric oxide synthase (NOS) activity in anesthetized rats subjected to 1 h of superior mesenteric ischemia or ischemia followed by reflow. NOS activity was measured in intestinal tissue homogenates as the conversion rate of (3)H-L-arginine to (3)H-L-citrulline. Our results demonstrate that intestinal ischemia leads to a decrease in NOS activity indicating lower NO(*) formation in the animal model. The attenuation in NOS activity was not reversed following 4 h of reperfusion. Western blot analysis revealed that the decline in enzyme activity was accompanied by reduced intestinal NOS III (endothelial constitutive NOS) expression. These findings provide biochemical evidence for impaired NO(*) formation machinery in intestinal I/R injury.
Khanna
A
A
Department of Pharmaceutics, State University of New York at Buffalo, 517 Hochstetter Hall, Amherst, New York 14260, USA.
Rossman
J E
JE
Fung
H L
HL
Caty
M G
MG
D000199:Actins / Q000378:metabolism; D000818:Animals; D007422:Intestines / Q000098:blood supply / Q000201:enzymology* / Q000293:injuries*; D008297:Male; D017538:Mesenteric Artery, Superior; D009569:Nitric Oxide / Q000096:biosynthesis; D019001:Nitric Oxide Synthase / Q000378:metabolism*; D052250:Nitric Oxide Synthase Type III; D051381:Rats; D017207:Rats, Sprague-Dawley; D015427:Reperfusion Injury / Q000201:enzymology* / Q000378:metabolism
D000199:Actins; D009569:Nitric Oxide; D019001:Nitric Oxide Synthase; D052250:Nitric Oxide Synthase Type III; C496316:Nos3 protein, rat