Is digoxin a designer oestrogen?

Na+/K+-ATPase α1 isoform mediates ouabain-induced expression of cyclin D1 and proliferation of rat sertoli cells

Novel roles for the interaction of cardiotonic steroids to Na(+)/K(+)-ATPase have been established in recent years. The aim of this study was to investigate the intracellular signaling events downstream the action of ouabain on Na(+)/K(+)-ATPase in Sertoli cell obtained from immature rats. Treatment of Sertoli cells with ouabain (1 μM) induced a rapid and transient increase in the extracellular signal-regulated kinase (ERK1/2 or MAPK3/1) and phosphatidylinositol 3-kinase (PI3K)/serine-threonine protein kinase (AKT) phosphorylation. Also, ouabain upregulated the expression of cyclin D1 and incorporation of [methyl-(3)H]thymidine, both of which were dependent on MAPK3/1 but not AKT intracellular cascade, as shown by pretreatment with MEK (MAP2K1/2) inhibitor U0126 and PI3K inhibitor wortmannin respectively. Moreover, the effect of ouabain on these proliferation parameters was completely prevented by phospho-cAMP response element-binding protein (CREB)/CREB-binding protein complex inhibitor KG501 and only partially by nuclear factor κB nuclear translocation inhibitor SN50. Pretreatment with estrogen receptor antagonist ICI 182780 showed that MAPK3/1 activation by ouabain does not involve this receptor. The Na(+)/K(+)-ATPase α1 isoform, but not α4, was detected in Sertoli cells, suggesting that ouabain effects in Sertoli cells are mediated via α1. Taken together, these results show a rapid ouabain action in the Sertoli cells, which in turn can modulate nuclear transcriptional events essential for Sertoli cell proliferation in a critical period of testicular development. Our findings are important to understand the role of ouabain in the testis and its possible implications in male infertility.

Electrocardiogram abnormalities predict angiographic coronary artery disease in women with chest pain: results from the NHLBI WISE Study

BACKGROUND AND HYPOTHESIS

Noninvasive risk stratification for coronary artery disease (CAD) isless accurate in women than in men. Based on recent reports that gender-specific exercise electrocardiogram (ECG) parameters predict CAD, we evaluated the independent predictive value of the resting ECG for angiographic CAD in women with chest pain.

METHODS

Women (n = 850, mean age 58 years) with chest pain in the NHLBI Women's Ischemia Syndrome Evaluation (WISE) underwent 12-lead ECG testing and quantitative coronary angiography.

RESULTS

Significant angiographic CAD (> or = 50% stenosis in > or = 1 coronary) was present in 39% of women. Q waves in < or = 2 contiguous ECG leads were present in 107 women (13%), including 49 of 657 (7%) without history of infarction. Among 585 women without prior infarction orrevascularization, 48% of those with Q waves in contiguous leads versus 26% of others, had significant CAD (p = 0.003; odds ratio [OR] = 2.5, 95% confidence interval [CI] = 1.3-4.8). Women with Q waves in < or = 2 inferior ECG leads were particularly likely to have CAD (63 vs. 26% of others, p < 0.001; OR = 4.6,95% CI = 2.0-10.8). Other ECG findings predictive of CAD were any ST-T abnormality (OR = 1.9,95% CI = 1.3-2.8) and T-wave inversion (OR = 2.4, 95% CI = 1.3-4.2). In risk-adjusted analysis, inferior Q waves and T-wave inversion independently predicted significant CAD. When considered together with radionuclide perfusion test results, T-wave inversion on resting ECG added significant independent predictive value (OR = 2.8, 95% CI = 1.1-7.2, p = 0.03).

CONCLUSIONS

Selected resting ECG parameters independently predict angiographic CAD in women with chest pain, including women who have also undergone radionuclide stress testing. Prospective studies should consider resting ECG parameters in diagnostic algorithms for CAD in women.