Quantitative mapping of cerebrovascular reactivity amplitude and delay with breath-hold BOLD fMRI when end-tidal CO quality is low.

Cerebrovascular reactivity (CVR), the ability of cerebral blood vessels to dilate or constrict in order to regulate blood flow, is a clinically useful measure of cerebrovascular health. CVR is often measured using a breath-hold task to modulate blood CO levels during an fMRI scan. Measuring end-tidal CO (PCO) with a nasal cannula during the task allows CVR amplitude to be calculated in standard units (vascular response per unit change in CO, or %BOLD/mmHg) and CVR delay to be calculated in seconds.

Delayed vacuolation in mammalian cells caused by hypotonicity and ion loss.

Prolonged exposure of mammalian cells to hypotonic environments stimulates the development of sometimes large and numerous vacuoles of unknown origin. Here, we investigate the nature and formation of these vacuoles, which we term LateVacs. Vacuolation starts after osmotic cell swelling has subsided and continues for many hours thereafter.

Intrinsic Molecular Proton Sensitivity Underlies GPR4 Effects on Retrotrapezoid Nucleus Neuronal Activation and CO-Stimulated Breathing.

An interoceptive homeostatic reflex monitors levels of CO/H to maintain blood gas homeostasis and rapidly regulate tissue acid-base balance by driving lung ventilation and CO excretion-this CO-evoked increase in respiration is the hypercapnic ventilatory reflex (HCVR). Retrotrapezoid nucleus (RTN) neurons provide crucial excitatory drive to downstream respiratory rhythm/pattern-generating circuits, and their activity is directly modulated by changes in CO/H RTN neurons express GPR4 and TASK-2, global deletion of which abrogates CO/H activation of RTN neurons and the HCVR. It has not been determined if the intrinsic pH sensitivity of these proton detectors is required for these effects.