Superior mesenteric artery is more important than inferior mesenteric artery in maintaining colonic mucosal perfusion and integrity in rats

Mucosal hemodynamics (by reflectance spectrophotometry) and mucosal damage (by histologic examination) following acute colonic ischemia were evaluated in different anatomic locations in the colon of anesthetized rats. The reflectance spectrophotometer provides an index of mucosal hemoglobin concentration (IHB) and an index of oxygen saturation of hemoglobin (ISO₂). The patterns of ischemia without congestion (IHB, ISO₂) during superior mesenteric artery occlusion, and ischemia with congestion (IHB, ISO₂) during portal vein occlusion, previously demonstrated in the stomach and duodenum, are also applicable to the colon. The significant linear correlations between changes (as percent of baseline) in IHB, ISO₂, and hydrogen gas clearance suggest that changes in these indices are adequate indicators of changes in colonic mucosal perfusion. Superior mesenteric artery ligation produced significant reductions in both indices, and an increase in damage in the mucosa of the cecum, transverse colon, splenic flexure, and left colon, but not the rectum. Inferior mesenteric artery ligation produced only slight reduction in these indices and minimal damage only in the mucosa of the splenic flexure. These results support the hypothesis that the superior mesenteric artery is more important than the inferior mesenteric artery in maintaining colonic perfusion and colonic mucosal integrity in the rat.Supported by the American Society for Gastrointestinal Endoscopy Career Development Award (H850208, H870212), Veterans Administration Medical Research Funds; and in part by research grants (0162-01, 0162-02; 0291-01) from the Smokeless Tobacco Research Council, Inc.; and by funds provided by the Cigarette and Tobacco Surtax Fund of the State of California through the Tobacco Related Disease Research Program of the University of California.     

乙醇对人绒毛孕酮分泌的影响

本工作利用灌流技术观察了四种不同浓度的乙醇(0.5％、1％、2.5％、5％)对妊娠早期人工流产新鲜胎盘绒毛分泌孕酮的影响。结果表明,乙醇具有促进孕酮分泌的作用,并存在剂量依赖的关系。提示乙醇可能破坏胎盘激素内分泌的平衡,从而影响胎儿的正常生长与发育。     

Artificial Circulation of the Liver: Machine Perfusion as a Preservation Method in Liver Transplantation

Due to the sharp increase in liver transplant candidates and the subsequent shortage of suitable donor livers, an extension of the current donor criteria is necessary. Simple cold storage, the current standard in organ preservation has proven to be insufficient to preserve extended criteria donor livers. Therefore a renewed interest grew toward alternative methods for liver preservation, such as hypothermic machine perfusion and normothermic machine perfusion. These “new” preservation methods were primarily assessed in rat models, and only a few clinically relevant large animal models have been described so far. This review will elaborate on these alternative preservation methods. Anat Rec, 291:735–740, 2008. © 2008 Wiley‐Liss, Inc.     

Microcirculation in the upper trapezius muscle during varying levels of static contraction,fatigue and recovery in healthy women —a study using percutaneous laser-Doppler flowmetry and surface electromyography

Summary Microcirculation in the upper portion of the trapezius muscle was measured percutaneously by continuous laser-Doppler flowmetry (LDF) during two 10-min series of alternating 1-min periods of static contraction and rest determined electromyographically (EMG). Stepwise increased contraction was induced by keeping the arms straight and elevated at 30, 60, 90 and 135°, which was repeated with a 1-kg load carried in each hand. Thereafter, fatigue and recovery were recorded while the subject kept her arms straight and elevated at 45° carrying the 1-kg hand load as long as possible, followed by rest with arms hanging and no load. A group of 16 healthy women of different ages was studied. Signal processing was done on line using a 386 SX computer. The LDF- and root-mean-square (rms) EMG signals were normalized. Spectrum analyses of EMG mean power frequency (MPF) and median spectrum frequency were performed. The rms-EMG increased significantly with an increase in the calculated shoulder torque (r=0.75). Accumulated local fatigue was indicated by a decrease in MPF with increased shoulder angle and added load (r = –0.54). Blood flow increased with increased shoulder angle (r=0.82, with hand loadr=0.62) and with increased shoulder torque (r=0.72), and also showed a significant increase with increased EMG activity (r=0.74). The LDF showed a negative correlation to MPF (r= –0.67), with increased values when MPF was lowered. During the endurance test, a moderate increase of LDF occurred which reached its maximum during the 1st min of recovery. Then, a slow return to the base level was recorded. The ability to increase the flow in the microcirculation with increasing muscle load was not diminished with age.     

Validation and advantages of FAWSETS perfusion measurements in skeletal muscle

This work discusses the strengths, limitations and validity of a novel arterial spin labeling technique when used specifically to measure perfusion in limb skeletal muscle. The technique, flow-driven arterial water stimulation with elimination of tissue signal (FAWSETS), offers several advantages over existing arterial spin labeling techniques. The primary goal of this study was to determine the perfusion signal response to changes in net hind limb flow that were independently verifiable. The range of perfusate flow was relevant to skeletal muscle during mild to moderate exercise. Localized, single voxel measurements were acquired from a 5 mm-thick slice in the isolated perfused rat hind limb at variable net flow rates. The results show that the perfusion signal is linearly proportional to net hind limb flow with a correlation coefficient of 0.974 (p = 0.0013). FAWSETS is especially well suited for studies of skeletal muscle perfusion, where it eliminates the need to compensate for magnetization transfer and arterial transit time effects. A conceptual discussion of the basic principles underlying these advantages is presented.     

A Simple Method for Isolation of Cardiomyocytes from Adult Rat Heart

A simple, economic, and sparing method for isolation of cardiomyocytes from adult rat heart is proposed. Ultrastructure of cardiomyocytes from suspension of freshly isolated cells was studied by light and transmission electron microscopy. The isolated cardiomyocytes were viable, had characteristic shape and size, and retained their normal structure. __________ Translated from Byulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 140, No. 9, pp. 357–360, September, 2005     

Estrogen receptor genotype modulates myocardial perfusion in young men

Most of the effects of estrogens are mediated by estrogen receptors. Vascular endothelial cells and smooth muscle cells express estrogen receptor (ESR1) in both genders. A long genotype group of a common thymine-adenine (TA) dinucleotide repeat polymorphism in the regulatory region of this gene has previously been related to coronary artery disease. The present study examined whether coronary blood flow is affected by this genotype. A total of 49 healthy men were genotyped by PCR and divided into three groups according to median number of the ESR1 promoter TA repeat (=19), i.e., in the short allele genotype group both alleles were of fewer than 19 repeats whereas in the long allele group both alleles were 19 repeats or more. The intermediate group comprised men who had one short and one long allele. Myocardial blood flow was measured by positron emission tomography using [¹⁵O]water, performed at rest and during adenosine stimulation. Men with long alleles had lower adenosine-stimulated coronary flow than those with short alleles and those with one short and one long allelle. Our results suggest that adenosine-stimulated myocardial perfusion is lower in subjects with ESR1 long alleles than the other TA repeat genotypes.     

A fast perfusion system for single cell physiology optimized for microscopes with water immersion objectives

A perfusion system was constructed which allows the fast application of different solutes underneath a water immersion objective. The perfusion system is mounted into the immersion objective by milling a slot into the frontal metal plate of the lens holder. It consists of a five-channel pipette fixed to the objective and solution reservoirs gated by computer controlled magnetic valves. Up to five different solutions can be applied to the specimen under study. The solution between objective and specimen is completely exchanged after 1–2 s as determined from fluorescence measurements. This arrangement is optimized for [Ca²⁺] measurements with a fluorescence measurement system in tissue slices, where upright microscopes are required. It offers the advantage of saving a micromanipulator for the perfusion pipette and facilitates a fast, reproducible and precise positioning of the perfusion system.     

The reflex effect of changes in renal perfusion on hindlimb vascular resistance in anaesthetized rabbits

This study was designed to characterise the response of the hindlimb vasculature to reduced renal perfusion in the anaesthetized rabbit and to elucidate whether the stimulus was dependent upon reduced renal perfusion pressure (RPP) or blood flow (RBF). Acute decreases in renal perfusion resulted in rapid and reversible increases in femoral perfusion (FPP). This vascular response was completely abolished following renal denervation indicating that the afferent component of the reflex is neurally mediated. Acute hindlimb responses to changes in renal perfusion pressure were present whether the limb was perfused with homologous blood or cross-perfused with blood from a donor rabbit, demonstrating that the efferent component of the response is also neurally mediated. There was a 28-s latency for initiation of the hindlimb vasoconstriction, which is consistent with recent evidence for renal autocoid stimulation of the afferent renal nerve receptors. Decreasing RPP indirectly, by altering flow, resulted in a hindlimb vasoconstriction below approximately 55 mm Hg (7.3 kPa) RPP or 15 ml/ min RBF. However, decreasing RPP by directly reducing pressure in graded steps resulted in increases in FPP, which reflected the changes in renal flow; thus during the autoregulatory phase, where flow did not change as pressure fell, FPP also remained stable. The results of these protocols suggest that a neurally mediated hindlimb vascular reflex is stimulated by decreased renal flow rather than pressure.     

Intracerebroventricular vasopressin reduces CSF absorption rate in the conscious goat

Summary Cerebrospinal fluid (CSF) levels of vasopressin (AVP) are elevated in some disorders associated with raised intracranial pressure. We have previously demonstrated that intracerebroventricular infusion of AVP in the conscious goat leads to elevation of intracranial pressure by a mechanism independent of changes in arterial blood pressure or circulating neurohypophysial peptide concentrations. We have now examined the effect of increasing CSF AVP levels on CSF dynamics using the technique of ventriculo-cisternal perfusion in the conscious goat. Intracerebroventricular perfusion with 5 pmol/min AVP in artificial CSF did not alter CSF formation rate but significantly reduced CSF absorption rate (24% decrease; p < 0.01), when compared with perfusion using artificial CSF alone. This AVP-mediated reduction in CSF absorption rate may represent increased resistance to resorption of CSF or may reflect the effect of raised intracranial pressure.