抄録
Intraventricular injection of histamine (Hi) significantly prolonged thiopental sleeping time at doses of 0.5μg or larger. Both 1-methylHi and imidazole-4-acetic acid, howere, did not affect thiopental narcosis. Pretreatment with α-fluoromethylhistidine diminished the effect of Hi, while histidine, metoprine and quinacrine prolonged thiopental narcosis. Injection with 2-methylHi did not affect thiopental sleeping time, while as in the case of Hi, 4-methylHi augmented the thiopental effect. In addition, H2-receptor blocking agents such as cimetidine, ranitidine and famotidine clearly antagonized Hi-induced prolongation of thiopental narcosis, while pyrilamine and chlorpheniramine had no effect. These results indicate that Hi-induced prolongation of thiopental narcosis appears to be exerted via H2 receptors and is, in some way, related to the Hi content in the brain.
