Expressional downregulation of neuronal-type NO synthase I in guinea pig skeletal muscle in response to bacterial lipopolysaccharide.

We have investigated the expression of neuronal-type NO synthase I (NOS I) and inducible-type NOS II in guinea pig skeletal muscle (diaphragm). Expression of NOS I mRNA and protein was highest in muscle of specific pathogen-free animals, lower in normally bred animals, and lowest in lipopolysaccharide (LPS)-treated animals. NOS II mRNA and protein levels were highest in muscle of LPS-treated animals. Elevated NOS activity in muscle from LPS-treated animals was less susceptible to the NOS I-selective inhibitor N(G)-nitro-L-arginine. Expressional downregulation of NOS I in sepsis may have implications for contractile function of skeletal muscle.