Determination of urinary methylhistamine excretion in male and female rats by gas chromatography with electron-capture detection

A gas-liquid chromatographic method for the determination of methylhistamine in urine is described. Methylhistamine is reacted with 2,6-dinitro-4-trifluoromethylbenzene sulfonic acid and the derivative thus formed is quantitated with electron-capture detection. The twenty-four hour urinary excretion of methylhistamine in the male rat is about five-fold greater than that in the female rat. Amino-guanadine, a diamine oxidase inhibitor, causes a four-to five-fold increase in methylhistamine excretion in both male and female rats. Treatment with pargyline, a monoamine oxidase inhibitor, causes only a small increase in methylhistamine excretion in male and female rats thereby suggesting that oxidative deamination of methylhistamine is a relatively minor pathway.