ABSTRACT
To assess environmental control on autonomic parameters between race and sex, we studied cross-sectionally, 119 West Point cadets of both sexes and of African-American and Caucasian descent. Specifically, heart period variability (HPV) and baroreceptor sensitivity index (BRSI) were assessed non-invasively. All participants had lived at the Academy for at least 1 year, had similar diets, ages, fitness status, access to medical care and educational backgrounds. Familial aggregation of hypertension was 46% for African-American and 30% for Caucasian, respectively. Autonomic outflow was assessed using the magnitude of the respiratory sinus arrhythmia (RSA) during sitting, standing and augmented breathing. Autocorrelations on 64 successive heart periods provided low frequency (LF) or high frequency (HF) distributions. The ratio of LF over HF was considered representative of sympathovagal balance. Baroreceptor sensitivity (BRSI) was assessed by recording cardiac deceleration in response to a Valsalva-induced increase in BP. Analysis of variance failed to reveal significant differences in any of these BP regulatory mechanisms between any of the groups. Prior investigations failed to control for the many environmental factors mentioned above and have therefore indicated significant epidemiological differences in the occurrence of hypertension between different races. Our results strongly suggest that environmental control seems to be an important modulator in the pathogenic mosaic of autonomic derangement, and should be strongly considered in future research.