Although recent high-resolution studies demonstrate the importance of nongravitational determinants for both pulmonary blood flow and ventilation distributions, posture has a clear impact on whole lung gas exchange. Deterioration in arterial oxygenation with repositioning from prone to supine posture is caused by increased heterogeneity in the distribution of ventilation-to-perfusion ratios. Th...

To study the effect of deafferentation on cortical areas activated by movement of the proximal muscles, we measured regional cerebral blood flow with positron emission tomography and 15O-labeled water. Flexion-extension movements of the right elbow before deafferentation were associated with an increase of regional cerebral blood flow in the primary sensorimotor area bilaterally, posterior supp...

BACKGROUND Experimental studies on the effects of alpha 2-adrenoceptors on regional coronary blood flow in normal and ischemic myocardium are highly controversial. A beneficial effect on regional ischemic myocardium has been demonstrated in different animal preparations with either alpha 2-adrenoceptor blockade or stimulation. Animal studies also demonstrated that postsynaptic alpha 2-adrenocep...

Background. Experimental studies on the effects of a2-adrenoceptors on regional coronary blood flow in normal and ischemic myocardium are highly controversial. A beneficial effect on regional ischemic myocardium has been demonstrated in different animal preparations with either a2-adrenoceptor blockade or stimulation. Animal studies also demonstrated that postsynaptic a2-adrenoceptors mediate v...

The effects of the administration of 0.5 or 1 mg/kg of 1-thyroxine for 3 or 16 days were studied in 55 New Zealand white rabbits. Heart size was 29% above control after 16 days of 1-thyroxine, despite lower body weights. In an anesthetized open-chest animal, regional microspectro-photometric observations of small arteries and veins to determine oxygen extraction were combined with regional bloo...

Regional Cerebral Blood Flow in Acute Stroke: Preliminary Experience With the Xenon Inhalation Method • The ""Xenon inhalation method of measuring regional cerebral blood flow was applied in serial studies comprising 100 measurements in 57 cases of acute hemiparesis and hemiplegia presumed due to arterial occlusion. Satisfactory data for analysis were obtained in over 95% of the cases studied. ...

Regional Cerebral Blood Flow in Acute Stroke: Preliminary Experience With the Xenon Inhalation Method • The ""Xenon inhalation method of measuring regional cerebral blood flow was applied in serial studies comprising 100 measurements in 57 cases of acute hemiparesis and hemiplegia presumed due to arterial occlusion. Satisfactory data for analysis were obtained in over 95% of the cases studied. ...

The changes in myocardial high energy phosphates and pH during regional ischemia, and their potential role in mediating functional abnormalities, is unclear. To determine the degree of regional blood flow reduction required to induce changes in high energy phosphates and pH, and to correlate these metabolic changes with alterations in blood flow, 31P nuclear magnetic resonance spectroscopy was ...

We evaluated the effects of breathing 35% stable xenon in 65% oxygen on regional cerebral blood flow and the electroencephalogram in 20 normal volunteers. We measured blood flow in 32 brain regions over both hemispheres with the xenon-133 intravenous injection technique in two protocols. In the first protocol (n = 10), a baseline study was followed by a second study during 5 minutes of breathin...