Search results for "Perfusion"
showing 10 items of 714 documents
Autoinhibition of noradrenaline release from the rat heart as a function of the biophase concentration. Effects of exogenous alpha-adrenoceptor agoni…
1984
1. Rat isolated perfused hearts with the right sympathetic nerves intact were loaded with 3H-(-)-noradrenaline. The nerves were stimulated with trains of 180 pulses at 3 Hz and at 10 min intervals. The overflow of 3H-noradrenaline and 3H-metabolites was determined by liquid scintillation spectrometry. 2. Clonidine (IC50 17 nM), oxymetazoline (IC50 63 nM), and α-methylnoradrenaline (apparent IC50 35 nM, determined in the presence of cocaine and propranolol) decreased the stimulation-evoked overflow of 3H-noradrenaline by 26, 49, and 78%, respectively, but not methoxamine up to 100 μM (propranolol present). Oxymetazoline and α-methyl-noradrenaline did not cause desensitization of the presynap…
Pulmonary effects of expiratory-assisted small-lumen ventilation during upper airway obstruction in pigs
2015
Summary Novel devices for small-lumen ventilation may enable effective inspiration and expiratory ventilation assistance despite airway obstruction. In this study, we investigated a porcine model of complete upper airway obstruction. After ethical approval, we randomly assigned 13 anaesthetised pigs either to small-lumen ventilation following airway obstruction (n = 8) for 30 min, or to volume-controlled ventilation (sham setting, n = 5). Small-lumen ventilation enabled adequate gas exchange over 30 min. One animal died as a result of a tension pneumothorax in this setting. Redistribution of ventilation from dorsal to central compartments and significant impairment of the distribution of ve…
Capillary flow and diameter changes during reperfusion after global cerebral ischemia studied by intravital video microscopy.
2004
The reaction of cerebral capillaries to ischemia is unclear. Based on Hossmann's observation of postischemic “delayed hypoperfusion,” we hypothesized that capillary flow is decreased during reperfusion because of increased precapillary flow resistance. To test this hypothesis, we measured cerebral capillary erythrocyte velocity and diameter changes by intravital microscopy in gerbils. A cranial window was prepared over the frontoparietal cortex in 26 gerbils anesthetized with halothane. The animals underwent either a sham operation or fifteen minutes of bilateral carotid artery occlusion causing global cerebral ischemia. Capillary flow velocities were measured by frame-to-frame tracking of…
Role of balloon occlusion for mononuclear bone marrow cell deposition after intracoronary injection in pigs with reperfused myocardial infarction
2008
Aims In clinical studies on cell therapy for acute myocardial infarction (MI), cells are usually applied by intracoronary infusion with balloon (IC/B). To test the utility of balloon occlusion, mononuclear bone marrow cell (MNC) retention after intracoronary infusion without balloon (IC/noB) was compared with IC/B and intramyocardial (IM) injection. Methods and results Four hours after LAD ligation in male pigs, reperfusion was allowed (confirmed by coronary angiography). Five days later, 1 × 108 autologous 111Indium-labelled MNC were injected IC/noB ( n = 4), IC/B ( n = 4), or IM ( n = 4). At 1 h the fraction of injected MNC that was detected in the heart was 4.1 ± 1.1% after IC/noB inject…
Serial assessments of microvascular obstruction by contrast-enhanced magnetic resonance predict contractile recovery and clinical outcome after reper…
2015
AIMS The purpose of the study was to investigate, using cardiac magnetic resonance (CMR), the presence and time course of microvascular obstruction (MO) in patients with acute myocardial infarction (AMI), and to test its relationship with cardiac remodeling and clinical outcomes. METHODS AND RESULTS 53 patients with AMI and successful percutaneous reperfusion underwent CMR examination at four separate timepoints: within the first 48 hours, at 10 days, at six and twelve months after infarction. MO was quantified immediately (early imaging) and 10 minutes (late imaging) after contrast administration in each session. The extent of MO decreased from early to late imaging at both the first and t…
Diagnostic performance of whole brain volume perfusion CT in intra-axial brain tumors: preoperative classification accuracy and histopathologic corre…
2012
Abstract Background To evaluate the preoperative diagnostic power and classification accuracy of perfusion parameters derived from whole brain volume perfusion CT (VPCT) in patients with cerebral tumors. Methods Sixty-three patients (31 male, 32 female; mean age 55.6 ± 13.9 years), with MRI findings suspected of cerebral lesions, underwent VPCT. Two readers independently evaluated VPCT data. Volumes of interest (VOIs) were marked circumscript around the tumor according to maximum intensity projection volumes, and then mapped automatically onto the cerebral blood volume (CBV), flow (CBF) and permeability Ktrans perfusion datasets. A second VOI was placed in the contra lateral cortex, as cont…
Suitability of the isolated perfused rat brain for studying effects on cerebral metabolism
1972
The concentrations of P-creatine, creatine, ATP, ADP, AMP, glycogen, glucose, glucose-6-P, fructose diphosphate, dihydroxyacetone-P, α-glycero-P, lactate and pyruvate were measured in the isolated perfused rat brain as well as in rat brain in vivo. Similar levels were observed in the isolated brain and in intact animals, and the values measured were in good accordance with those described in the literature. Only the pyruvate and lactate content were significantly higher in the isolated brain but the lactate/pyruvate ratio remained unchanged. An anesthetic or ischemia caused just the same effects on energy metabolism of the isolated rat brain as described for intact animals. Thus, 1.5 mM phe…
Tissue optical perfusion pressure: a simplified, more reliable, and faster assessment of pedal microcirculation in peripheral artery disease
2020
Oscillometry is an alternative to continuous-wave Doppler (cw-Doppler) to determine peripheral artery disease (PAD) severity using the ankle-brachial index (ABI). cw-Doppler ABI differentiates systolic pressure of ATP and ADP where either one of both values in most patients is higher (high) and the other value is lower (low). In contrast, oscillometric ABI measures the strongest signal and hence misses the lower value. Both do not take pedal perfusion into consideration. Simultaneous determination of tissue microperfusion cares for pedal PAD. ABI was determined by cw-Doppler and oscillometry. Tissue optical perfusion pressure (TOPP) was taken from the first toe using photoplethysmography. 3…
D-Glucose and fluid reabsorption in proximal surface tubule of the rat kidney
1972
Hexose reabsorption in the kidney was investigated by microperfusion of proximal cortical rat nephrons with Ringer's solution containingD-glucose (2.5, 5.0 and 18.0 mM/l), 3-O-methylD-glucose (4.5 mM/l) orD-fructose (18.0 mM/l) at perfusion rates of 20 or 40×10−6 ml/min. Inulin was used as a reference for fluid reabsorption. 1. The fraction of fluid reabsorbed was independent of the glucose concentration but it decreased when the perfusion rate increased from 20–40×10−6 ml/min. 2. At 18.0 mM/l the % glucose reabsorption was equal to the % fluid reabsorption. This equality was independent of the perfusion rate, (20 or 40×10−6 ml/min), indicating 1:1 coupling with net isotonic fluid reabsorpt…
Effect of chronic exercise on glucose uptake and activities of glycolytic enzymes measured regionally in rat heart.
1989
Regional glucose uptake in perfused hearts, and the activities of several glycolytic enzymes contributing to the glucose metabolism in perfused and nonperfused hearts were studied in male and female rats after 8–9 weeks of swimming training. The left ventricular glucose uptake showed a transmural gradient in the sedentary animals, the subendocardial uptake being 30% and 12% higher than that of the subepicardial layer in the males and females, respectively. Swimming exercise abolished the left ventricular glucose uptake gradient in male rats, and in female rats an opposite gradient was found, the subepicardial uptake being 23% higher than the subendocardial uptake. The activities of phosphof…