Resting regional brain activity and functional connectivity varies with resting blood pressure but not muscle sympathetic nerve activity in normotensive humans

Abstract

IntroductionMean arterial pressure (MAP) is tightly controlled by the brain, with the rostroventrolateral medulla (RVLM) ‐ the final output nucleus for muscle sympathetic nerve activity (MSNA) ‐ playing a particularly important role. The aim of this study was to investigate the relationships between regional cerebral blood flow (rCBF) ‐ a proxy marker of neural activity ‐ and MAP and MSNA in young, healthy normotensive subjects.MethodsPseudocontinuous arterial spin labeling (pCASL) and functional magnetic resonance imaging (fMRI) of the brain were performed immediately following a recording of MSNA and BP in 31 normotensive subjects (13 females, 18 males; mean±SE age: 23.3±3.8 y). Subjects were divided into groups with lower (78.8±1.1 mmHg, n=15) and higher (95.9±1.6 mmHg, n=16) MAP, as well as lower (7.5±0.8 bursts/min, n=16) and higher (22.3±1.9 bursts/min, n=15) MSNA.ResultsRegional cerebral blood flow correlated positively with resting MAP in the RVLM and dorsolateral pons, as well as in the insular, prefrontal and cingulate cortices. Furthermore, functional connectivity analysis revealed that the insular and prefrontal cortices displayed greater resting connectivity within the RVLM in the group with lower MAP, but not in the group with higher MAP. However, no significant differences in rCBF were found when subjects were divided on the basis of MSNA.ConclusionsThese results suggest that small differences in resting MAP are associated with significant differences in resting activity and functional connectivity within brain regions known to contribute to cardiovascular control. It remains to be seen how these relationships are affected in hypertensive individuals.Support or Funding InformationNational Health & Medical Research Council of Australia (GTN1100040)This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.