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Relation of autonomic activity to plasminogen activator inhibitor-1 plasma concentration and the role of body mass index.von Känel R, Nelesen RA, Ziegler MG, Mausbach BT, Mills PJ, Dimsdale JE Department of General Internal Medicine, University Hospital Berne, Switzerland. We hypothesized an association between heart rate variability (HRV) and plasminogen activator inhibitor (PAI)-1 that would be affected by body mass index (BMI). We determined PAI-1 antigen in plasma and the low-frequency power, high-frequency power and the low-frequency/high-frequency power ratio from surface electrocardiogram data using spectral analysis in a sample of 116 black and white men and women (mean +/- SE age, 36.8 +/- 0.7 years). Regression equations controlled for age, gender, ethnicity, smoking status, blood pressure, and BMI. We specifically tested whether BMI would moderate or mediate the relationship between HRV and PAI-1. There were bivariate correlations between PAI-1 and low-frequency power (r = -0.24, P = 0.010), high-frequency power (r = -0.41, P < 0.001), and the low-frequency/high-frequency power ratio (r = 0.19, P = 0.042). High-frequency power emerged as an independent predictor of PAI-1 levels (beta = -0.20, P = 0.040; DeltaR = 0.027) after controlling for covariates. The BMI significantly mediated the relationship between PAI-1 levels and low-frequency power (t = -2.77, P = 0.006) and high-frequency power (t = -2.99, P = 0.003). In conclusion, reduced parasympathetic activity (i.e. decreased high-frequency power) accounted for a small but significant amount of the variance in elevated PAI-1 levels. More apparent, higher BMI explained a significant proportion of the variance in the relationship between depressed sympathetic and parasympathetic activity and elevated plasma PAI-1 concentration. Published 2 May 2007 in Blood Coagul Fibrinolysis, 18(4): 353-9.
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