α-Fluoromethyl histidine: Inhibition of histidine decarboxylase in pylorus ligated rat

α-Fluoromethyl histidine is an irreversible inhibitor of histidine decarboxylase. The injection of a single dose to pyloric-ligated rats inhibits gastric mucosal histidine decarboxylase in a dosedependent manner but does not modify histamine content and gastric acid secretion even at the highest dose used. Administration of cimetidine increases histidine decarboxylase activity, decreases histamine level in gastric mucosa and inhibits gastric acid secretion. The co-administration of α-fluoromethyl histidine blocks the augmentation in enzyme activity, maintains lowered histamine level and prolongs the antisecretory action of cimetidine.