Gravitational Transitions Increase Posterior Cerebral Perfusion and Systemic Oxidative-nitrosative Stress: Implications for Neurovascular Unit Integrity.

The present study examined if repeated bouts of micro- and hypergravity during parabolic flight (PF) alter structural integrity of the neurovascular unit (NVU) subsequent to free radical-mediated changes in regional cerebral perfusion. Six participants (5♂, 1♀) aged 29 ± 11 years were examined before, during and after a 3 h PF and compared to six sex and age-matched (27 ± 6 years) normogravity controls. Blood flow was measured in the anterior (middle cerebral artery, MCA; internal carotid artery, ICA) and posterior (vertebral artery, VA) circulation (duplex ultrasound) in-flight over the course of 15 parabolas.

Does respiratory drive modify the cerebral vascular response to changes in end-tidal carbon dioxide?

New Findings: What is the central question of this study? There is an interaction between the regulatory systems of respiration and cerebral blood flow, because the mediator (CO ) is the same for both physiological systems. We examined whether the traditional method for determining cerebrovascular reactivity to CO is modified by changes in respiration. What is the main finding and its importance? Cerebrovascular reactivity was modified by voluntary changes in respiration during hypercapnia.