Gamma-tocopherol enhances sodium excretion as a natriuretic hormone precursor
2004
Uto, H. (Ochanomizu Univ., Tokyo (Japan). Inst. of Environmental Science for Human Life) | Kiyose, C. | Saito, H. | Ueda, T. | Nakamura, T. | Igarashi, O. | Kondo, K.
Endogenous natriuretic factors are believed to be responsible for extracellular fluid homeostasis in mammals. A new endogenous natriuretic factor, Loma Linda University-alpha (LLU-alpha) has recently been proven to be a 2,7,8-trimethyl-2-(2'-carboxyethyl)-6-hydroxychroman (gamma-CEHC). which is a metabolite of gamma-tocopherol (gamma-Toc). The purpose of this study was to investigate whether gamma-Toc could accelerate sodium excretion into rat urine as a natriuretic hormone precursor. Male SD strain rats were divided into two groups; one was a control diet group, while the other was a high NaCl group (50 g/kg diet). Next, the two groups were each subdivided into two groups consisting of a placebo group and a gamma-Toc group. Alter the oral administration of one experimental dose of 20 mg gamma-Toc or placebo, rat urine was collected at 6 h intervals for 24 h. and then the urine volume, sodium and potassium and gamma-CEHC content were determined. gamma-Toc increased in the urine volume of the high-NaCl intake group. The sodium excretion in the high-NaCl group given gamma-Toc was 8.29+-2.2O g. while in the control group given gamma-Toc it was 6.24+- 1.49 g from 12-18 h. In contrast, the potassium excretion in the rat urine did not change in any of the groups. Our findings suggested that gamma-Toc accelerates the degree of sodium excretion in rats with a high sodium intake.
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