Dose-response relations in urinary excretion of trimethylselenonium in the rat.
75Se-labeled selenite was administered to fasting rats by orogastric intubation (1.5-3000 micrograms/kg body wt). Urine was collected and characterized for total radioactivity as well as for radiolabeled trimethylselenonium (TMSe). At lower doses of selenite (up to 500 micrograms/kg body wt), 30% of the administered dose was excreted. At higher doses of selenite, fractional urine excretion decreased as a function of the dose. The observed decrease in fractional urine excretion was not caused by changes in the absorption of the administered radiolabel. There was a direct relationship between the amount of the administered dose of selenite (up to 1500 micrograms/kg body wt) and the proportion of urinary [75Se] excreted as TMSe. Pretreatment with seleno compounds (10 or 100 micrograms Se/kg body wt as selenite, or selenomethionine) for 35 d before a challenge dose of [75Se]selenite did not influence the excretion of total [75Se] or of [75Se]TMSe in urine. Ingestion of a choline-deficient diet, which should deplete the availability of methyl groups, did not have any effect on excretion of total [75Se] or of [75Se]TMSe in urine after a challenge dose of [75Se]selenite (500 micrograms/kg body wt). The data presented here permit the following conclusions: 1) Production of TMSe is dose dependent, 2) production of TMSe from a single acute dose does not depend on the history of selenium intake and 3) rats fed a methyl-deficient diet are able to eliminate Se via formation of TMSe.
Zeisel
S H
SH
Department of Pathology, Boston University School of Medicine, MA 02118.
Ellis
A L
AL
Sun
X F
XF
Pomfret
E A
EA
Ting
B T
BT
Janghorbani
M
M
D000818:Animals; D002796:Choline Deficiency / Q000652:urine; D002851:Chromatography, High Pressure Liquid; D009942:Organometallic Compounds / Q000652:urine*; D051381:Rats; D011919:Rats, Inbred Strains; D020887:Selenious Acid; D012643:Selenium / Q000008:administration & dosage* / Q000494:pharmacology / Q000652:urine*; D018036:Selenium Compounds; D012644:Selenium Radioisotopes; D012645:Selenomethionine / Q000494:pharmacology
D009942:Organometallic Compounds; D018036:Selenium Compounds; D012644:Selenium Radioisotopes; D012645:Selenomethionine; D020887:Selenious Acid; D012643:Selenium; C003717:trimethylselenonium