In vivo effects of 17β-estradiol on cardiac Na(+)/K(+)-ATPase expression and activity in rat heart

Abstract

In this study the in vivo effects of estradiol in regulating Na(+)/K(+)-ATPase function in rat heart was studied. Adult male Wistar rats were treated with estradiol (40μg/kg, i.p.) and after 24h the animals were sacrificed and the heart excised. Following estradiol administration, cardiac Na(+)/K(+)-ATPase activity, expression of the α1 subunit, and phosphorylation of the α1 subunit were significantly increased. These animals also had significantly decreased levels of digoxin-like immunoreactive factor(s). Na(+) levels were also significantly reduced but to a level that was still within the normal physiological range, highlighting the ability of the Na(+)/K(+)-ATPase to balance the ionic composition following treatment with estradiol. Estradiol treated rats also showed increased phosphorylation of protein kinase B (Akt), and extracellular-signal-regulated kinase 1/2 (ERK1/2). We therefore suggest a role for Akt and/or ERK1/2 in estradiol-mediated regulation of cardiac Na(+)/K(+)-ATPase expression and activity in rat heart.

Keywords: 5-bromo-4-chloro-3-indoyl phosphate/nitro blue tetrazolium chloride; ALP; Akt; BCIP/NBT; CV; DLIF; ER; ERK1/2; Estradiol; Extracellular-signal-regulated kinase ½; FPIA; HRP; IR; IRS1; LV; Na(+)/K(+)-ATPase; PBS; PI3K; PVDF; Protein kinase B; RIA; Sodium potassium adenosine-triphosphatase; TBS; TC; alkaline phosphatase; cardiovascular; digoxin-like immunoreactive factor(s); estrogen receptor; extracellular-signal-regulated kinase 1/2; fluorescence polarization immunoassay; horseradish peroxidase; insulin receptor substrate 1; insulin resistance; left ventricle; phosphate-buffered saline; phosphatidylinositol-3 kinase; polyvinylidence difluoride; protein kinase B; radioimmunoassay; sodium/potassium-adenosine triphosphatase; total cholesterol; tris (hydroxymethyl) aminomethane buffer saline.