PARTICIPATION OF NITRIC-OXIDE IN MOUSE ANAPHYLACTIC HYPOTENSION

Mouse hen egg-white lysozyme-specific anaphylaxis was estimated by mon itoring changes in blood pressure by using a tail-cuff method. Stimula tion of histamine H-1 receptors of the vascular endothelium was sugges ted to be critical for mouse anaphylactic hypotension, because pretrea tment with diphenhydramine but not with cimetidine completely inhibite d the hypotension. Nitric oxide (NO) was indicated to play an importan t role in mouse anaphylaxis, because N-G-nitro-L-arginine methyl ester , a NO synthase inhibitor, significantly blocked the hypotension while a large amount of L-arginine, a precursor of NO synthesis, restored t he hypotension.