Abstract 036: Family History of Hypertension and Sympathetic Neural Reactivity to Mental Stress in Humans

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A number of recent studies have highlighted large inter-individual variability of muscle sympathetic nerve activity (MSNA) responsiveness to mental stress in humans. It remains unclear if family history of hypertension (FHH+) influences this variability. The purpose of this study was to examine blood pressure (BP) and MSNA responsiveness to mental stress in a large and generalizable cohort of young adults, and control for a variety of baseline factors that can influence MSNA reactivity. We hypothesized that subjects with FHH+ would demonstrate greater sympathoexcitation to mental stress than subjects without a family history of hypertension (FHH-). A total of 85 subjects from recently published (within 3 yrs; n=37) and ongoing (n=48) studies were examined. Data are presented on 45 subjects with complete MSNA recordings (15 FHH+ subjects and 30 FHH- subjects; 31 men and 14 women; age, 18 to 33 years). Heart rate (HR), BP, and MSNA were recorded during five min of supine rest and five min of mental stress (via mental arithmetic). Age, sex, body mass index, baseline mean arterial pressure (MAP), and baseline HR were identified as covariates. Baseline MSNA and HR were not statistically different between FHH+ and FHH- groups (p>0.05), whereas MAP was higher in FHH+ (84±2 and 79±2 mmHg; p<0.05). Mental stress increased MSNA in FHH+ subjects ([[Unable to Display Character: ∆]]4.4±1.5 bursts/min), but not FHH- subjects ([[Unable to Display Character: ∆]]1.0±0.2 bursts/min; time х group, p<0.01). Differences between FHH+ and FHH- groups remained when MSNA was normalized to heart rate ([[Unable to Display Character: ∆]]2.8±1.0 bursts/100 heart beats vs. [[Unable to Display Character: ∆]]-3.1±0.5 bursts/100 heart beats; time х group, p<0.05). Mental stress increased MAP ([[Unable to Display Character: ∆]]11±1 mmHg and [[Unable to Display Character: ∆]]10±1 mmHg; p<0.001) and HR ([[Unable to Display Character: ∆]]18±4 beats/min and [[Unable to Display Character: ∆]]17±2 beats/min; p<0.001) in FHH+ and FHH- subjects, but these increases were not different between groups (time х group, p≥0.05). In conclusion, our findings demonstrate that FHH+ is associated with greater MSNA reactivity to acute mental stress when compared to FHH- individuals.