Intestinal edema decreases intestinal contractile activity via decreased myosin light chain phosphorylation.
OBJECTIVE
The purpose of this study was to investigate the effects of interstitial edema on intestinal contractile activity.


METHODS
Randomized animal study.


METHODS
University laboratory.


METHODS
Male Sprague-Dawley rats.


METHODS
Intestinal edema was induced in rats by a combination of fluid infusion and mesenteric venous hypertension. Rats were divided into four groups: CONTROL, sham; RESUS, saline infusion only; RESUS+VH, saline infusion and venous hypertension; and VH, venous hypertension only. Edema development, basal contractile activity, maximum agonist-induced contractile response (measured as total force generation during the first 2 mins after carbachol treatment), and myosin light chain phosphorylation were measured in the distal small intestine.


RESULTS
The amount of interstitial fluid, indicated by the wet-to-dry ratio, increased significantly in both the RESUS and RESUS+VH groups as early as 30 mins after surgery compared with the CONTROL group. Whereas the tissue fluid remained significantly elevated in the RESUS+VH group up to 6 hrs after surgery, the RESUS group wet-to-dry ratios returned to CONTROL group levels by 2 hrs after surgery. Basal contractile activity was significantly less in the RESUS+VH group compared with either the RESUS group or the CONTROL group 6 hrs after surgery. Maximum contractile response decreased significantly in the RESUS+VH group compared with the RESUS group. Basal contractile activity and maximum contractile response did not change significantly in the VH group compared with the CONTROL group. The phosphorylated fraction of myosin light chain was significantly lower in the RESUS+VH group compared with the CONTROL group at 0.5, 2, and 6 hrs after surgery.


CONCLUSIONS
We conclude that edema decreases myosin light chain phosphorylation, leading to decreased intestinal contractile activity.
Uray
Karen S
KS
Division of Pediatric Surgery, Department of Surgery, University of Texas Medical School at Houston, TX, USA.
Laine
Glen A
GA
Xue
Hasan
H
Allen
Steven J
SJ
Cox
Charles S
CS
D000704:Analysis of Variance; D000818:Animals; D016207:Cytokines / Q000378:metabolism; D004487:Edema / Q000503:physiopathology*; D045823:Ileus / Q000503:physiopathology*; D007421:Intestine, Small / Q000378:metabolism; D008297:Male; D009119:Muscle Contraction; D009130:Muscle, Smooth; D018994:Myosin Light Chains; D010766:Phosphorylation; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley
D016207:Cytokines; D018994:Myosin Light Chains