Document Type
Article
Publication Date
8-18-2023
Journal
American journal of physiology. Heart and circulatory physiology
URL with Digital Object Identifier
https://doi: 10.1152/ajpheart.00301.2023
Abstract
Bursts of muscle sympathetic nerve activity (MSNA) and the ensuing vasoconstriction are pivotal determinants of beat-by-beat blood pressure regulation. Although age and sex impact blood pressure regulation, how these factors affect the central and peripheral arcs of the baroreflex remains unclear. In 27 young (25[3] years) males (YM; n=14) and females (YF; n=13) and 23 older (71[5] years) males (OM; n=11) and females (OF; n=12) femoral artery blood flow, blood pressure and MSNA were recorded for 10 minutes of supine rest. Sympathetic baroreflex sensitivity (i.e., central arc) was quantified as the relationship between diastolic blood pressure and MSNA burst incidence. Signal averaging was used to determine sympathetic vascular transduction into leg vascular conductance (LVC) for 12 cardiac cycles following MSNA bursts (i.e., peripheral arc). Older adults demonstrated attenuated sympathetic transduction into LVC (both PP=0.004-0.032). YM (r2=0.36; P=0.032) and OM (r2=0.51; P=0.014) exhibited an inverse relationship between the central and peripheral arcs of the baroreflex, whereas females did not (YF: r2=0.03; P=0.621, OF: r2=0.06; P=0.445). MSNA burst incidence was inversely related with sympathetic transduction in YM and OF (range: P=0.03-0.046), but not in YF or OM (range: P=0.360-0.603). These data indicate that age is associated with attenuated sympathetic vascular transduction whereas age- and sex-specific changes are present in the relationship between the central and peripheral arcs of the baroreflex regulation of blood pressure.