Effects of Nitric Oxide Produced from Bovine Alveolar Macrophages on the Growth of Pasteurella haemolytica A1

ABSTRACT

Nitric Oxide (NO) is an important mediator in various pathological conditions. The list of agents known to activate the NO pathway continues to expand and now includes bacterial products, cytokines, cAMP-elevating agents, trauma, and ozone. The activation of the L-arginine-dependent NO pathway via NO synthase is an important mechanism to stimulate both antimicrobial capability and cytotoxicity of phagocytes. NO has both beneficial and detrimental effects on host responses including lung injury. The effects of NO on the host were intensively investigated in lung injury, bovine pneumonic pasteurellosis (51). However, there was no description about the effect on the primary agent of the disease, Pasteurella haemolytica Al. Therefore, we investigated the effect of NO produced from bovine alveolar macrophages on the growth of Pasteurella haemolytica Al which is the primary agent of bovine pneumonic pasteurellosis. With the exogenous source of NO, sodium nitroprusside (SNP), the growth of the bacterium was dose-dependently inhibited by NO produced from SNP when measured by XTT colorimetric assay and standard plate count method. Also, same effect was observed in AM-derived NO. The effect was bacteriostatic rather than bactericidal.