title: Gamma-tocopherol enhances sodium excretion as a natriuretic hormone precursor.
abstract: 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. After 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+/-2.20 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.
authors.affiliation: Institute of Environmental Science for Human Life, Ochanomizu University, 2-1-1 Ohtsuka, Bunkyo-ku, Tokyo 112-8610, Japan.
authors.forename: Harumi
authors.initials: H
authors.lastname: Uto
authors.forename: Chikako
authors.initials: C
authors.lastname: Kiyose
authors.forename: Hisako
authors.initials: H
authors.lastname: Saito
authors.forename: Tadahiko
authors.initials: T
authors.lastname: Ueda
authors.forename: Takaharu
authors.initials: T
authors.lastname: Nakamijra
authors.forename: Osamu
authors.initials: O
authors.lastname: Igarashi
authors.forename: Kazuo
authors.initials: K
authors.lastname: Kondo
mesh_terms: D000284:Administration, Oral; D000818:Animals; D000975:Antioxidants / Q000008:administration & dosage / Q000494:pharmacology*; D002839:Chromans / Q000378:metabolism / Q000652:urine; D007668:Kidney / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D011188:Potassium / Q000652:urine; D011422:Propionates / Q000378:metabolism / Q000652:urine; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley; D012964:Sodium / Q000652:urine*; D017673:Sodium Chloride, Dietary / Q000008:administration & dosage / Q000493:pharmacokinetics*; D014556:Urine / Q000502:physiology; D024504:gamma-Tocopherol / Q000008:administration & dosage / Q000494:pharmacology*
chemical_list: D000975:Antioxidants; D002839:Chromans; D011422:Propionates; D017673:Sodium Chloride, Dietary; C107690:2,7,8-trimethyl-2-(beta-carboxyethyl)-6-hydroxychroman; D024504:gamma-Tocopherol; D012964:Sodium; D011188:Potassium