Barium Activates Rat Cerebellar Nitric Oxide Synthase

Abstract

Ba²⁺ is known to pass through N-methyl-D-aspartate receptor channels and cause an increase in cGMP levels in rat cerebella. In the present study, we compared the activation of rat cerebellar nitric oxide synthase (NOS) by Ba²⁺ with that produced by Ca²⁺. Both cations stimulated L-citrulline formation in the presence of calmodulin in identical fractions eluted from an anion exchange column with a salt gradient. EC₅₀ values for Ca²⁺ and Ba²⁺ were 200 nM and 50 μΜ, respectively. The IC₅₀ of N^G-monomethyl-L-arginine was the same (200 nM). These indicate a possible action of Ba²⁺ on NOS through the calmodulin-dependent pathway.