Barium activates rat cerebellar nitric oxide synthase.
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 microM, respectively. The IC50 of NG-monomethyl-L-arginine was the same (200 nM). These indicate a possible action of Ba2+ on NOS through the calmodulin-dependent pathway.
Yamazaki
J
J
Department of Toxicology and Pharmacology, Faculty of Pharmaceutical Sciences, University of Tokyo, Japan.
Urushidani
T
T
Nagao
T
T
D000818:Animals; D001120:Arginine / Q000378:metabolism; D001464:Barium / Q000494:pharmacology*; D002118:Calcium / Q000494:pharmacology*; D002147:Calmodulin / Q000494:pharmacology; D002531:Cerebellum / Q000187:drug effects* / Q000201:enzymology; D002852:Chromatography, Ion Exchange; D002956:Citrulline / Q000378:metabolism; D006152:Cyclic GMP / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects; D007928:Lethal Dose 50; D008297:Male; D019001:Nitric Oxide Synthase / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D016194:Receptors, N-Methyl-D-Aspartate / Q000187:drug effects* / Q000378:metabolism
D002147:Calmodulin; D016194:Receptors, N-Methyl-D-Aspartate; D001464:Barium; D002956:Citrulline; D001120:Arginine; D019001:Nitric Oxide Synthase; D006152:Cyclic GMP; D002118:Calcium