Retrograde blood flow in the internal jugular veins of humans with hypertension may have implications for cerebral arterial blood flow

Greater increase in internal carotid artery shear rate during aerobic interval compared to continuous exercise in healthy adult men

“…Further, exercise‐induced increases in flow‐mediated dilation (FMD) in the systemic vasculature, as an index of endothelial function, were deemed not different between the exercise protocols (Lyall et al, 2019). It is noteworthy that exercise increases the retrograde SR in the systemic vasculature (Lyall et al, 2019); however, retrograde SR is absent in the cerebral vasculature (Rodrigues et al, 2020). In fact, in this present study, the reversal of the ICA blood flow was absent even with the higher workloads during aerobic Interval‐Ex.…”

“…In contrast, in the systemic vasculature, there are muscle contractions and functional sympatholysis that impact the flow patterns in active skeletal muscle, while thermoregulation and sympathetic vasoconstriction influence the flow patterns in the inactive limbs. Another possible mechanism is associated with that retrograde SR is absent in the cerebral vasculature (Rodrigues et al, 2020). In the systemic vasculature, both the aerobic and resistance exercise have been determined to increase both the antegrade and retrograde SR that typically contribute to the upregulation of the NO pathway (Tinken et al, 2009) and impairment in the endothelial function (Thijssen et al, 2009; Tinken et al, 2009), respectively.…”

“…In the systemic vasculature, both the aerobic and resistance exercise have been determined to increase both the antegrade and retrograde SR that typically contribute to the upregulation of the NO pathway (Tinken et al, 2009) and impairment in the endothelial function (Thijssen et al, 2009; Tinken et al, 2009), respectively. However, antegrade SR typically dominates in the cerebral circulation (Rodrigues et al, 2020). It is noteworthy that this different hemodynamic property between the cerebral and systemic vasculatures may highlight the contrasting flow profiles to which these anatomically distinct but functionally integrated vascular beds were exposed (Connolly et al, 2017).…”

“…These findings indicate in the peripheral artery that the increases in the retrograde and the associated oscillatory SR present a detrimental stimulus to the endothelium (Thijssen et al, 2009). However, in contrast to the peripheral vasculature, the reversal of the cerebral blood flow is much smaller or absent; thus, retrograde and oscillatory SRs are likely to be minimal in the cerebral circulation (Rodrigues et al, 2020). In addition to the sustained elevation in the SR, exercise causes transient disturbances in the redox homeostasis in the cells and tissues.…”

“…It is noteworthy that in the systemic vasculature, acute leg exercise increases the brachial retrograde SR, irrespective of low exercise workload (Simmons et al, 2011), and increases in retrograde SR augments oscillatory SR (Lyall et al, 2019). In contrast, retrograde SR has not been identified in the cerebrovasculature (Rodrigues et al, 2020). Therefore, exercise‐induced changes in the SR are likely to be site‐specific.…”