Abstract P101: Sympathetic Transduction In Young Adults With A Family History Of Hypertension

Abstract

Exaggerated sympathetic transduction (i.e., the vascular response to a burst of muscle sympathetic nerve activity; MSNA) has recently been demonstrated in certain populations of young adults at risk for future hypertension. However, it remains unknown the degree to which a family history of hypertension (FH), a risk factor for future hypertension, may influence sympathetic transduction. Purpose: The purpose of this study was to test the hypothesis that a +FH augments the pressor response following spontaneous bursts of MSNA at rest in young adults. A secondary purpose was to compare the influence of a +FH on sympathetic transduction between young men and women. Methods: We retrospectively examined beat-by-beat blood pressure (finger photoplethysmography) and MSNA (peroneal microneurography) in 21 +FH young adults (9 +FH men: 26 ± 2 yr, 25 ± 4 kg/m 2 , 12 +FH women: 22 ± 2 yr, 22 ± 3 kg/m 2 ) and 15 -FH young adults (8 -FH men: 24 ± 5 yr, 25 ± 2 kg/m 2 , 7 -FH women: 22 ± 3 yr, 23 ± 3 kg/m 2 ) during 10 minutes of supine rest. Signal averaging was used to characterize changes in BP for the 10 cardiac cycles following a spontaneous MSNA burst. Resting baseline variables were compared using 2-way ANOVAs. Mean arterial pressure (MAP) changes over 10 cardiac cycles following a burst of MSNA were compared using a 2-way repeated measures ANOVA (Time, FH status) and a 3-way repeated measures ANOVA (Time, FH status, Sex). Data are presented as mean ± SD. Results: Resting MAP (+FH: 86 ± 9 vs. -FH: 82 ± 7 mmHg; P = 0.14) and resting MSNA (+FH: 10 ± 6 vs. -FH: 9 ± 6 mmHg; P = 0.65) did not differ by FH status. The increase in MAP over the 10 cardiac cycles following a spontaneous burst of MSNA did not differ by FH status (Time, P < 0.0001; FH status, P = 0.17; Time * FH status, P = 0.70) and this influence did not differ between the sexes (Time * FH status, P = 0.58; Time * Sex, P = 0.06; Time * FH status * Sex, P = 0.99). Conclusions: These preliminary data suggest that spontaneous MSNA bursts do not elicit greater increases in MAP in +FH young adults, regardless of sex. Additional data are needed to determine the interactions between FH status, sex, and sympathetic transduction. Supported by NIH Grant P20 GM 113125, P20 GM 103446, U54 GM 104941, K99/R00 HL133414, and The University of Delaware Research Foundation.