DECREASED ILEAL MUSCLE CONTRACTILITY AND INCREASED NOS-II EXPRESSION INDUCED BY LIPOPOLYSACCHARIDE

This study was designed to determine if an increase in nitric oxide sy nthase (NOS) activity induced by lipopolysaccharide (LPS) is associate d with increases in NOS II protein and mRNA abundance and with altered ileal longitudinal muscle contractility. Strips of muscle taken from LPS-treated, but not control, animals exhibited reduced in vitro contr actility when L-arginine was a component of the physiological salt sol ution. This reduction was reversed by N-omega-nitro-L-arginine (L-NNA) , a competitive inhibitor of NOS. Full-thickness segments of jejunum, ileum, and colon taken 5 h after LPS injection exhibited increased NOS activity, NOS II immunoreactivity, and NOS II mRNA abundance. Increas ed NOS II immunoreactivity and mRNA abundance also were detected in il eal muscle strips taken from LPS-treated animals. These data confirm t he reported effects of LPS on intestinal NOS activity and indicate tha t it can be attributed, at least in part, to an increase in NOS II mRN A and protein abundance. Furthermore, the data suggest that an LPS-ind uced increase in NOS II may lead to a decrease in ileal muscle contrac tility.