抄録
We investigated the roles of nitric oxide (NO) and isozymes of NO synthase in rat anaphylactic hypotension. Effects of inhibitors of endothelial NOS (eNOS), inducible NOS (iNOS) and neuronal NOS (nNOS), using NG-nitro-L-arginine methyl ester (L-NAME; 10 mg/kg), aminoguanidine (100 mg/kg), and 7-nitroindazole (7-NI; 50mg/kg), respectively, were determined on the antigen-induced hypotension and portal hypertension in conscious SD rats sensitized with the ovalbumin antigen. Systemic arterial pressure (Psa) and portal venous pressure (Ppv) were directly and simultaneously measured. The control rats injected with antigen showed a decrease in Psa along with an increase in Ppv, but did not die within 24 hrs after antigen injection. In rats pretreatment with L-NAME, anaphylactic hypotension was attenuated only at the early stage of 10 min after antigen, but portal hypertension was augmented, resulting in fatal outcome within 12 hr after antigen. In contrast, the pretreatment with a nNOS inhibitor, 7-NI, substantially attenuated anaphylactic hypotension over 20 min after antigen, while iNOS inhibitor of aminoguanidine did not affect it. In conclusion, NO derived from eNOS and nNOS, but not iNOS, is involved in anaphylactic hypotension, but inhibition of eNOS is lethal in conscious rats. [J Physiol Sci. 2008;58 Suppl:S182]
