High cardiorespiratory fitness in early to late middle age preserves the cortical circuitry associated with brain-heart integration during volitional exercise

Abstract

This study tested the hypothesis that high cardiorespiratory fitness (peak oxygen uptake) preserves the cortical circuitry associated with cardiac arousal during exercise in middle- to older-aged individuals. Observations of changes in heart rate (HR) and in cortical blood oxygenation level-dependent (BOLD) images were made in 52 healthy, active individuals (45-73 yr; 16 women, 36 men) across a range of fitness (26-66 ml·kg·min). Seven repeated bouts of isometric handgrip (IHG) at 40% maximal voluntary contraction force were performed with functional magnetic resonance imaging at 3 T, with each contraction lasting 20 s and separated by 40 s of rest. HR responses to IHG showed high variability across individuals. Linear regression revealed that cardiorespiratory fitness was not a strong predictor of the HR response ( = 0.09). In a region-of-interest analysis both the IHG task and the HR time course correlated with increased cortical activation in the bilateral insula and decreased activation relative to baseline in the anterior and posterior cingulate and medial prefrontal cortex (MPFC). -Test results revealed greater deactivation at the MPFC with higher fitness levels beyond that of guideline-based activity. Therefore, whereas high cardiorespiratory fitness failed to affect absolute HR responses to IHG in this age range, a select effect was observed in cortical regions known to be associated with cardiovascular arousal. Our first observation suggests that fitness does not strongly predict the heart rate (HR) response to a volitional handgrip task in middle- to older-aged adults. Second, the BOLD response associated with the handgrip task, and with the HR time course, was associated with response patterns in the cortical autonomic network. Finally, whereas high cardiorespiratory fitness failed to affect absolute HR responses to isometric handgrip in this age range, a select effect was observed in cortical regions known to be associated with cardiovascular arousal, beyond that achieved through healthy active living.

Neurotransmitter networks in mouse prefrontal cortex are reconfigured by isoflurane anesthesia

“…The prefrontal cortex was targeted because of its significant contribution to neurological diseases (Xu et al 2019), the regulation of breathing (Herrero et al 2018;Ramirez and Baertsch 2018), and cardiovascular function (Hassan et al 2013;Wood et al 2017). Isoflurane anesthesia was used as a tool to cause loss of wakefulness and to create a stable behavioral state during dialysis sample collection (Flint et al 2010).…”

The Cardiovascular Stress Response as Early Life Marker of Cardiovascular Health: Applications in Population-Based Pediatric Studies—A Narrative Review

“…In women baseline CSA was 10.7 ± 2.6mm 2 , and increased 1.4 ± 9.6% with IHE Men: HR increase: 20,0% Systolic BP increase: 10,7% Diastolic BP increase: 15,9%: RPP increase: 33,9% Women: HR increase: 17,2% Systolic BP increase: 8,0% Diastolic BP increase: 17,9% RPP increase: 28,1% Norton (2013) [ 96 ] 29 subjects: age: 21–80 years 40% MVC FMRI of the brain The average change in HR from baseline was 6BPM Norton (2015) [ 97 ] 23 healthy subjects: age: 63 years 17 patients with CAD: age: 59 years 7 repeated bouts at 40% MVC with each contraction lasting 20 s and separated by 40 s of rest FMRI of the brain HR during exercise in control participants was greater than CAD patients Specifically, young individuals (25 ± 4 year) have a larger HR response (6–15 beats/min) to a similar relative IHE tension Rokamp (2014) [ 98 ] 11 healthy subjects: age: 24 ± 3 years Squeeze 30–60 times per minute with as much effort as possible FMRI of the brain Diastolic BP increase: 4 mmHg Mean BP increase: 5 mmHg No significant changes were observed for SBP and HR Verbree (2017) [ 99 ] 20 healthy subjects: age: 30 years The first minute at 80% MVC to be directly followed by 4 min at 60% MVC Middle cerebral artery HR increase: 11.2 ± 1.7% Williamson (2003) [ 100 ] 8 healthy subjects: age: 26 ± 3 years IHE beginning at 40% MVC until 15 mmHg BP increase FMRI of the brain Mean BP increase: 14,9% HR increase: 7 ± 3 BPM Wong (2007) [ 101 ] 17 healthy subjects: age: 25 ± 4 years 3 × 30 s blocks separated by 1 min of rest at 5% or 35% MVC FMRI of the brain HR and MAP were increased in the 35% MVC trials but not the 5%MVC trials. Both the left and right hand trials elicited similar cardiovascular responses Wood (2017) [ ...…”