Microvascular research
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Microvascular research · Dec 2009
Topical application of cerium nitrate prevents burn edema after burn plasma transfer.
Thermal injuries of more than 20% body surface area (BSA) result in systemic capillary leakage with subsequent edema. This can similarly be induced by burn plasma transfer (BPT) from burned individuals to healthy rats. We evaluated if cerium nitrate (CN) bathing can prevent edema after BPT. ⋯ CN bathing after 10 and 120 min reduces mediator levels in burned individuals. Therefore, BPT after CN application does not induce burn shock anymore. Burn edema is partially independent from leukocyte activation because CN significantly influences macromolecular leakage whereas leukocyte activation is not significantly altered.
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Microvascular research · Dec 2009
Poroelastic theory of transcapillary flow: effects of endothelial glycocalyx deterioration.
The luminal surface of endothelial cells is lined with a carbohydrate-rich layer known as the endothelial glycocalyx. Identification of the structural properties of the glycocalyx has led investigators to examine its various functions and it has since been recognized as playing a role in many physiological processes, one of which is the regulation of fluid and protein exchange across the capillary wall. Experimental observations in which the glycocalyx was degraded in rat myocardial capillaries showed fluid accumulation in the tissue, suggesting that the glycocalyx acts as a protective barrier against edema. ⋯ Upon enzymatic treatment the properties of the glycocalyx, such as its thickness and permeability, will be modified, and our purpose here is to investigate quantitatively how changes in these parameters affect the magnitude of the fluid filtration through the capillary wall. We compare our results with both experimental data as well as other theoretical models where applicable, discussing the implications of the models as well as the limitations of comparison. This work provides the basis for further experiments that may better characterise many of the parameters involved in this process.
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Microvascular research · Sep 2009
Tissue viability imaging: microvascular response to vasoactive drugs induced by iontophoresis.
When one is studying the physiology of the cutaneous microcirculation there is a need for relevant non-invasive and versatile techniques. In this study we used a new optical device, the tissue viability imager (TiVi), to map changes in cutaneous microvascular concentrations of red blood cells during iontophoresis of vasoactive substances (noradrenaline (NA) and phenylephrine (Phe) for vasoconstriction and acetylcholine (ACh) and sodium nitroprusside (SNP) for vasodilatation). We aimed to present data both individually and pooled, using a four-variable logistic dose response model that is commonly used in similar in vitro vascular studies. ⋯ Fitting the TiVi data to the dose response model resulted in ED(50)-values with narrow confidence intervals and acceptable r(2) values. Mean ED(50)-values for the TiVi did not differ significantly from similar values obtained using laser Doppler. Results further seem to suggest that when the blood perfusion increases during vasodilatation in skin the initial phase relies mainly on an increase in red blood cell concentration whereas the further perfusion increase is due to an increase in red blood cell velocity.
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Microvascular research · Sep 2009
Hepatic microvascular pressure during anaphylactic shock in anesthetized rats.
Hepatic venoconstriction plays a significant role in anaphylactic hypotension in anesthetized rats. The purpose of this study is to determine whether the primary site of anaphylactic venoconstriction in the liver venous circulation occurs prior to or distal to the sinusoidal capillaries. We also determined whether the hepatic blood volume is increased during anaphylactic hypotension. ⋯ Pre-sinusoidal constriction during anaphylactic shock in anaesthetized rats increased the portal venous pressure while the hepatic venular pressure only increased slightly and transiently. This predominant pre-sinusoidal constriction is accompanied by a decrease in liver volume.
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Microvascular research · Jun 2009
Electrokinetic effect of the endothelial glycocalyx layer on two-phase blood flow in small blood vessels.
Blood flow behaves differently at the microvascular level than they do at upper levels of circulating systems. The endothelial glycocalyx layer on the luminal surface of blood vessels plays a significant role in regulating blood flow and blood cell movement in microvascular networks. For instance, previous experimental studies showed that the endothelial glycocalyx layer causes additional resistance to blood flow in small blood vessels. ⋯ The question remains: do these electrostatic charges retard blood flow in small blood vessels according to the electroviscous effect? Here, a theoretical model is proposed to investigate the electrochemical effects of the endothelial glycocalyx layer on two-phase non-Newtonian blood flow in small blood vessels. Results show that electrostatic charges on the endothelial glycocalyx layer induce negligible effect to blood flow. Therefore, we can attribute the cause of additional resistance by the endothelial glycocalyx layer mainly to other mechanisms, such as, the glycocalyx constituted proteins acting as a flow barrier.