Intravenous administration of 2,7,8‐trimethyl‐2‐( β ‐carboxyethyl)‐6‐hydroxy chroman ( γ ‐CEHC) to rats and determination of its plasma concentration and urinary sodium excretion

A natriuretic hormone, 2,7,8‐trimethyl‐2‐( β ‐carboxyethyl)‐6‐hydroxy chroman ( γ ‐CEHC) was administered intravenously to male Sprague–Dawley rats and the plasma concentration of γ ‐CEHC along with urinary sodium (Na + ) excretion was investigated. The plasma γ ‐CEHC concentrations were uorimetrically determined by a column‐switching HPLC method consisting of both phenyl and octadecyl silica columns, following a pre‐column uorescence derivatization with a uorescence reagent, 4‐ N , N ‐dimethylaminosulfonyl‐7‐piperazino‐2,1,3‐benzoxadiazole (DBD‐PZ). In rats fed with a high‐NaCl (8.0%) diet, plasma γ ‐CEHC concentrations rapidly decreased by 20% in 15–45 min after the adminstration of γ ‐CEHC, while Na + excretion gradually increased with time. Considering these results, the Na + excretion effect appeared not to be associated with plasma γ ‐CEHC concentration. In addition, attempts were made to examine a main urinary metabolite of γ ‐CEHC, a large amount of 6‐ O ‐sulfated γ ‐CEHC found to be present in the urine using an HPLC‐tandem mass spectrometry. Thus, it is plausible that γ ‐CEHC was easily metabolized to 6‐ O ‐sulfated metabolite and excreted into urine in rats. Copyright © 2004 John Wiley & Sons, Ltd.