Left ventricular mass, stroke volume, and ouabain-like factor in essentialhypertension

Many patients with essential hypertension (EH) exhibit increased left ventr icular mass. Similarly, elevated circulating levels of an endogenous ouabai nlike factor (OLF) have been described in some but not all patients with EH . Moreover, ouabain has a hypertrophic influence on isolated cardiac myocyt es, Accordingly, we investigated relationships among plasma OLF, left ventr icular mass, and cardiac function in patients with EH. Plasma OLF was deter mined in 110 normotensive subjects and 128 patients with EH. Echocardiograp hic parameters and humoral determinants were measured in EH. Plasma OLF lev els were increased (P<0.0001) in patients with EH (377+/-19 pmol/L) versus normotensive (253+/-53 pmol/L) subjects. The distribution of plasma OLF was unimodal in normotensives, whereas it was bimodal in EH. Twenty-four-hour diastolic ambulatory blood pressure was slighter higher in EH with high OLF compared with EH with normal OLF (93.2+/-1.14 versus 89.4+/-1.33 mm Hg, P= 0.03). Left ventricular mass index and stroke volume in EH with high OLF we re greater than in EH with normal OLF (101.9+/-3.3 versus 86.1+/-2.5 g/m(2) , P=0.0003, and 57.10+/-1.48 versus 52.30+/-1.14 mL/m(2), P=0.02, respectiv ely), although heart rate was slower (74.2+/-1.3 versus 80.5+/-1.3 bpm, P=0 .005). Multiple regression analysis that tested the influence of body mass index, age, gender, 24-hour blood pressure, and OLF on left ventricular mas s revealed independent contributions of systolic (13.2%) and diastolic (12. 4%) blood pressure and plasma OLF (11.6%) to left ventricular mass. We conc lude that approximate to 50% of patients with uncomplicated EH have elevate d-high circulating OLF levels, higher diastolic blood pressure, greater lef t ventricular mass and stroke volume, and reduced heart rate. We propose th at the OLF affects cardiovascular function and structure and should be cons idered as a factor that contributes to the risk of morbid events.