Cardiac vagal withdrawal when moving from supine to an upright posture may be independent of respiratory sinus arrhythmia. Further, ventilatory efficiency of an upright lung may improve with clustering of heart beats during inhalation. We studied healthy human subjects (n=8, 6 male) during supine rest (SUP) and 80 degrees head-up tilt (HUT). ECG and expired breath were sampled continuously to d...

With a growing need for specific biomarkers in vascular diseases, there has been a surging interest in mapping cerebrovascular reactivity (CVR) of the brain. This index can be measured by conducting a hypercapnia challenge while acquiring blood-oxygenation-level-dependent (BOLD) signals. A BOLD signal increase with hypercapnia is the expected outcome and represents the majority of literature re...

SUMMARY Cerebral blood flow, oxygen, glucose, lactate, and pyruvate metabolism were measured in 13 subjects with completed stroke. Cerebral blood flow and oxygen consumption were reduced, glucose consumption and pyruvate production were normal, and lactate production was increased, suggesting a shift from aerobic to anaerobic cerebral glycolysis. To test this hypothesis, cerebral blood flow and...

Background. Carbon dioxide inhalation is known to induce an emotion similar to spontaneous panic in Panic Disorder patients. The affective response to carbon dioxide in healthy subjects was not clearly characterized yet. Methodology/ Principal Findings. Sixty-four healthy subjects underwent a double inhalation of four mixtures containing respectively 0, 9, 17.5 and 35% CO2 in compressed air, fo...

Measurement of regional cerebral blood flow (rCBF) was performed in 6 healthy baboons during ventilation with 35% stable xenon in artificial air. rCBF was measured with the intraarterial xenon-133 method. EEG was recorded continuously. All CBF areas of interest over one hemisphere reacted in the same way. Mean flow increased during short-term exposure to stable xenon and decreased if stable xen...

The contribution of carotid chemoreceptors to hypercapnia-induced mesenteric venoconstriction was examined in 12 α-chloralose-anesthetized rabbits (1.0-1.6 kg). Surgical preparation consisted of a tracheotomy, femoral arterial and venous cannulation, and a midline laparotomy through which a 13-cm loop of ileum was exteriorized and superfused with physiological salt solution. Mesenteric vein dia...

The N2O technique was used in 6 human subjects to measure cerebral blood flow and metabolism during hypoxia and hypercapnia induced by the inhalation of 10% O2-5% CO2. Ventilation increased from 7.7 to 46.3 liters/min; Pao2 decreased from 88 to 62 mm Hg; Pacoo increased from 38 to 45 mm Hg (for each P < . 0 1 ) . Mean cerebral blood flow increased from 56 to 97 ml/100 g/min ( P < .01). Because ...

Reactivity of Cerebral Blood Flow to CO, in Patients With Transient Cerebral Ischemic A Hacks • Cerebral blood flow and its ability to increase in response to inhalation of 6% CO2 was measured in six patients with a history of transient ischemic attacks in the internal carotid distribution and in ten normal control subjects. Flow was measured with a method which uses time concentration curves m...

An index of cerebral perfusion reserve (RES%), defined as the percent change of regional cerebral blood flow over baseline per mm Hg of end-tidal CO2 tension, was determined for each middle cerebral artery (MCA) territory in patients with unilateral carotid distribution transient ischemic attacks or minor cerebrovascular accidents and was compared with that of age-matched, neurologically normal...

CO2 laser-photoacoustic technology was used to investigate the suitability of ethylene as biomarker for active smoking with electronic cigarettes (E-cigarettes) vs. traditional cigarettes (T-cigarettes). Higher levels of ethylene in the composition of breath after T-cigarettes inhalation was found in comparison with the inhalation with E-cigarettes. The goal of this study was to explore and ver...