Gamma-tocotrienol, a vitamin E homolog, is a natriuretic hormone precursor.
2,7,8-Trimethyl-2-(beta-carboxyethyl)-6-hydroxychroman (gamma-CEHC), a metabolite of gamma-tocopherol and gamma-tocotrienol, was identified as a new endogenous natriuretic factor. However, gamma-tocopherol and gamma-tocotrienol, both precursors of gamma-CEHC, have never directly been observed to have natriuretic potency. Thus, we investigated whether gamma-tocotrienol could cause natriuresis and diuresis in rats. The rats were divided into two groups that were given a control or a high-sodium diet for 4 weeks, and then subdivided into placebo and gamma-tocotrienol subgroups given only corn oil-removed vitamin E and oil supplemented with gamma-tocotrienol, respectively. After oral administration of three experimental doses, rat urine was collected and gamma-CEHC, urine volume, sodium, and potassium content were determined. Only in rats given a high-NaCl diet did gamma-tocotrienol accelerate and increase sodium excretion, showing no effect on potassium excretion. Sodium excretion in the high-NaCl group given gamma-tocotrienol was 5.06 +/- 2.70 g/day, and in the control group given gamma-tocotrienol, 0.11 +/- 0.06 g/day. Furthermore, gamma-tocotrienol affected urine volume in the specific condition of high-NaCl body stores and gamma-tocotrienol supplementation. In this study, we found that gamma-tocotrienol, one of the natural vitamin E homologs, stimulates sodium excretion in vivo, suggesting that gamma-tocotrienol possesses a hormone-like natriuretic function.
Saito
Hisako
H
Institute of Environmental Science for Human Life, Ochanomizu University, Bunkyo-ku, Tokyo, 112-8610, Japan.
Kiyose
Chikako
C
Yoshimura
Hiroyuki
H
Ueda
Tadahiko
T
Kondo
Kazuo
K
Igarashi
Osamu
O
D000818:Animals; D002839:Chromans / Q000737:chemistry* / Q000378:metabolism* / Q000652:urine; D008297:Male; D015394:Molecular Structure; D011188:Potassium / Q000652:urine; D011422:Propionates / Q000652:urine; D051381:Rats; D017207:Rats, Sprague-Dawley; D012964:Sodium / Q000652:urine; D014810:Vitamin E / Q000031:analogs & derivatives* / Q000737:chemistry* / Q000378:metabolism*; D014811:Vitamin E Deficiency
D002839:Chromans; D011422:Propionates; D014810:Vitamin E; C107690:2,7,8-trimethyl-2-(beta-carboxyethyl)-6-hydroxychroman; C013649:plastochromanol 8; D012964:Sodium; D011188:Potassium