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Arteriole

The Experts below are selected from a list of 279 Experts worldwide ranked by ideXlab platform

Wilhelm Kriz – 1st expert on this subject based on the ideXlab platform

  • The Vascular Pole of the Renal Glomerulus of Rat – The vascular pole of the renal glomerulus of rat.
    Advances in Anatomy Embryology and Cell Biology, 1998
    Co-Authors: Marlies Elger, Tatsuo Sakai, Wilhelm Kriz

    Abstract:

    : In the present study we provide a detailed structural analysis of the vascular pole of superficial and midcortical glomeruli of the rat kidney. A description of the juxtaglomerular portions of the afferent and efferent Arterioles, the extraglomerular mesangium and the glomerular stalk is included. The specific structural elaboration of the epithelial transition from the podocytes to the parietal epithelium is emphasized, with particular attention to the arrangement of the cytoskeleton and its connections to extracellular matrix elements. The branching patterns of the afferent and efferent Arterioles are quite different. Immediately at the glomerular entrance, the afferent Arteriole divides into its primary branches. In contrast, the efferent Arteriole has a specific outflow segment (consisting of an intraglomerular portion and a portion associated with the extraglomerular mesangium) established by the confluence of capillary tributaries deep inside the glomerular tuft. Just at the transition from inside to outside, this segment includes a prominent narrow portion with conspicuous endothelial cells bulging into the vessel lumen. The extraglomerular mesangium has been found to represent a solid block of cells and matrix filling the space between the macula densa and both Arterioles and extending into the entrance funnel. Peripherally located extraglomerular mesangial cells attach to the outer aspect of the parietal basement membrane. As a whole, the extraglomerular mesangium occludes the glomerular tuft. The results appear relevant with respect to four major aspects: (1) a support function counteracting the expansile forces resulting from the high intraglomerular pressures, (2) a direct functional influence of the afferent on the efferent Arteriole, resulting from their narrow assemblage at the glomerular entrance, (3) a specific shear stress receptor function of the intraglomerular segment of the efferent Arteriole, and (4) fluid leakage from the glomerular tuft through the stalk and the extraglomerular mesangium into the cortical interstitium. 1. The glomerulus is a high-pressure compartment; expansile forces continuously tend to expand glomerular capillaries, the glomerular stalk, and the glomerular entrance. Counteracting centripetal forces at the vascular pole appear to be developed as circular forces by the cytoskeleton of podocytes and parietal cells surrounding the glomerular entrance and as interconnecting forces between both Arterioles and between opposing walls of the glomerular entrance, as well as of the glomerular stalk. These interconnecting forces are developed by the extraglomerular mesangium which–as a whole–forms a spiderlike closure device holding the glomerular entrance together. In addition, the extraglomerular mesangium develops occluding forces, allowing a gradual pressure drop between the glomerular stalk and the macula densa. 2. At the glomerular entrance, the outflow segment of the efferent Arteriole is narrowly associated with the bifurcation of the afferent Arteriole. Both are enclosed together in a common compartment surrounded by the glomerular basement membrane; there is no pressure barrier individually encompassing each vessel. Therefore, it may readily be suggested that the hydrostatic pressure of the afferent Arteriole acts on the efferent Arteriole. As a consequence, the luminal width of the efferent Arteriole at this site, i.e., its resistance, may be directly modified by the pressure in the afferent Arteriole. 3. The efferent Arteriole at the transition of the intraglomerular segment to the segment that passes through the extraglomerular mesangium has a conspicuously narrow portion with endothelial cells protruding into the vessel lumen. In addition, this segment is prominent by the expression of the neuronal type of nitric oxide synthase. We therefore propose that this segment acts as a specific shear stress receptor. The possible relevance of a shear stress receptor at this site would be

  • the vascular pole of the renal glomerulus of rat
    Advances in Anatomy Embryology and Cell Biology, 1998
    Co-Authors: Marlies Elger, Tatsuo Sakai, Wilhelm Kriz

    Abstract:

    1 Introduction.- 2 Material and Methods.- 3 Results.- 3.1 The Opening in Bowman’s Capsulex.- 3.1.1 Transition of the GMB into the PBM.- 3.1.2 Transition from Podocytes to Parietal Cells.- 3.2 Glomerular Arterioles.- 3.2.1 Afferent Arteriole.- 3.2.2 Efferent Arteriole.- 3.3 Extraglomerular Mesangium.- 3.3.1 EGM Cells.- 3.3.2 EGM Matrix.- 3.3.3 EGM Relationships to Neighboring Structures.- 3.3.4 Glomerular Stalk.- 4 Discussion.- 4.1 Stabilization of the Vascular Pole.- 4.2 Regulation of Glomerular Blood Flow and Filtration.- 4.3 Integration of Vascular Pole Structures into the Juxtaglomerular Apparatus.- 4.4 Fluid Leakage Through the Glomerular Stalk.- 5 Summary.- References.

  • the vascular pole of the renal glomerulus of rat
    Advances in Anatomy Embryology and Cell Biology, 1998
    Co-Authors: Marlies Elger, Tatsuo Sakai, Wilhelm Kriz

    Abstract:

    : In the present study we provide a detailed structural analysis of the vascular pole of superficial and midcortical glomeruli of the rat kidney. A description of the juxtaglomerular portions of the afferent and efferent Arterioles, the extraglomerular mesangium and the glomerular stalk is included. The specific structural elaboration of the epithelial transition from the podocytes to the parietal epithelium is emphasized, with particular attention to the arrangement of the cytoskeleton and its connections to extracellular matrix elements. The branching patterns of the afferent and efferent Arterioles are quite different. Immediately at the glomerular entrance, the afferent Arteriole divides into its primary branches. In contrast, the efferent Arteriole has a specific outflow segment (consisting of an intraglomerular portion and a portion associated with the extraglomerular mesangium) established by the confluence of capillary tributaries deep inside the glomerular tuft. Just at the transition from inside to outside, this segment includes a prominent narrow portion with conspicuous endothelial cells bulging into the vessel lumen. The extraglomerular mesangium has been found to represent a solid block of cells and matrix filling the space between the macula densa and both Arterioles and extending into the entrance funnel. Peripherally located extraglomerular mesangial cells attach to the outer aspect of the parietal basement membrane. As a whole, the extraglomerular mesangium occludes the glomerular tuft. The results appear relevant with respect to four major aspects: (1) a support function counteracting the expansile forces resulting from the high intraglomerular pressures, (2) a direct functional influence of the afferent on the efferent Arteriole, resulting from their narrow assemblage at the glomerular entrance, (3) a specific shear stress receptor function of the intraglomerular segment of the efferent Arteriole, and (4) fluid leakage from the glomerular tuft through the stalk and the extraglomerular mesangium into the cortical interstitium. 1. The glomerulus is a high-pressure compartment; expansile forces continuously tend to expand glomerular capillaries, the glomerular stalk, and the glomerular entrance. Counteracting centripetal forces at the vascular pole appear to be developed as circular forces by the cytoskeleton of podocytes and parietal cells surrounding the glomerular entrance and as interconnecting forces between both Arterioles and between opposing walls of the glomerular entrance, as well as of the glomerular stalk. These interconnecting forces are developed by the extraglomerular mesangium which–as a whole–forms a spiderlike closure device holding the glomerular entrance together. In addition, the extraglomerular mesangium develops occluding forces, allowing a gradual pressure drop between the glomerular stalk and the macula densa. 2. At the glomerular entrance, the outflow segment of the efferent Arteriole is narrowly associated with the bifurcation of the afferent Arteriole. Both are enclosed together in a common compartment surrounded by the glomerular basement membrane; there is no pressure barrier individually encompassing each vessel. Therefore, it may readily be suggested that the hydrostatic pressure of the afferent Arteriole acts on the efferent Arteriole. As a consequence, the luminal width of the efferent Arteriole at this site, i.e., its resistance, may be directly modified by the pressure in the afferent Arteriole. 3. The efferent Arteriole at the transition of the intraglomerular segment to the segment that passes through the extraglomerular mesangium has a conspicuously narrow portion with endothelial cells protruding into the vessel lumen. In addition, this segment is prominent by the expression of the neuronal type of nitric oxide synthase. We therefore propose that this segment acts as a specific shear stress receptor. The possible relevance of a shear stress receptor at this site would be

Gerald A. Meininger – 2nd expert on this subject based on the ideXlab platform

  • arteriolar dilation produced by venule endothelium derived nitric oxide
    Microcirculation, 1997
    Co-Authors: Jeff C Falcone, Gerald A. Meininger

    Abstract:

    OBJECTIVE: We conducted bioassay experiments to determine whether nitric oxide produced by endothelial cells (endothelial-derived nitric oxide, or EDNO) within large venules could act to dilate Arterioles. METHODS: In these experiments parallel segments of first-order Arterioles and venules were isolated from skeletal muscle and were cannulated in series with a glass connecting tube (length: 300-500 microns). Arterioles were mechanically denuded of endothelium by a delicate yet abrasive rubbing technique. Venular endothelium remained intact. Endothelial denudation of Arterioles was confirmed by the absence of dilation during exposure to acetylcholine (10(-6) mol/L). The cannulated vessels were pressurized to 30 cm H2O and the Arterioles pre-constricted by approximately 50% with norepinephrine (10(-10) mol/L). RESULTS: Topical applications of acetylcholine (10(-6) mol/L) or bradykinin (10(-9) mol/L) during luminal perfusion from venule to Arteriole produced significant arteriolar dilation. In contrast, a slight arteriolar constriction was observed when the direction of flow was reversed (i.e., Arteriole to venule) in the presence of either acetylcholine (10(-6) mol/L) or bradykinin (10(-9) mol/L). Inhibition of venular EDNO with NG-monomethyl-L-arginine (L-NMMA; 10(-5) mol/L; 1 hour) completely abolished the arteriolar dilation observed in response to acetylcholine or bradykinin during venule to Arteriole perfusion. CONCLUSIONS: These results demonstrate that venular-derived EDNO can relax arteriolar vascular smooth muscle.

  • Arteriolar Dilation Produced by Venule Endothelium‐Derived Nitric Oxide
    Microcirculation, 1997
    Co-Authors: Jeff C Falcone, Gerald A. Meininger

    Abstract:

    OBJECTIVE: We conducted bioassay experiments to determine whether nitric oxide produced by endothelial cells (endothelial-derived nitric oxide, or EDNO) within large venules could act to dilate Arterioles. METHODS: In these experiments parallel segments of first-order Arterioles and venules were isolated from skeletal muscle and were cannulated in series with a glass connecting tube (length: 300-500 microns). Arterioles were mechanically denuded of endothelium by a delicate yet abrasive rubbing technique. Venular endothelium remained intact. Endothelial denudation of Arterioles was confirmed by the absence of dilation during exposure to acetylcholine (10(-6) mol/L). The cannulated vessels were pressurized to 30 cm H2O and the Arterioles pre-constricted by approximately 50% with norepinephrine (10(-10) mol/L). RESULTS: Topical applications of acetylcholine (10(-6) mol/L) or bradykinin (10(-9) mol/L) during luminal perfusion from venule to Arteriole produced significant arteriolar dilation. In contrast, a slight arteriolar constriction was observed when the direction of flow was reversed (i.e., Arteriole to venule) in the presence of either acetylcholine (10(-6) mol/L) or bradykinin (10(-9) mol/L). Inhibition of venular EDNO with NG-monomethyl-L-arginine (L-NMMA; 10(-5) mol/L; 1 hour) completely abolished the arteriolar dilation observed in response to acetylcholine or bradykinin during venule to Arteriole perfusion. CONCLUSIONS: These results demonstrate that venular-derived EDNO can relax arteriolar vascular smooth muscle.

Paul Mitchell – 3rd expert on this subject based on the ideXlab platform

  • computer assisted retinal vessel measurement in an older population correlation between right and left eyes
    Clinical and Experimental Ophthalmology, 2003
    Co-Authors: Harry Leung, Jie Jin Wang, Elena Rochtchina, Tien Yin Wong, Larry D. Hubbard, Ronald Klein, Paul Mitchell

    Abstract:

    : This study assessed the correlation between computer-assisted retinal vessel measurements of right and left eyes, from subjects in a defined, community-based older population. Retinal photographs from participants in the Blue Mountains Eye Study were digitized. All retinal Arterioles and venules located 0.5-1.0 disc diameters from the optic disc margin were identified and a computer program measured their diameters. Pearson correlation (R2) statistic was used to assess the correlation in a random subsample of 1546 images. Substantial correlation between right and left eye measurements was found for summary indices of retinal Arterioles (R2 = 0.70) and venules (R2 = 0.77). Higher correlation was found for intragrader (R2 0.75-079) than for intergrader assessment (R2 0.67-0.72). Moderate correlation was found in Arteriole-to-venule ratio assessed by the same (R2 = 0.57) or different (R2 = 0.52) graders. Measurements from one eye can thus adequately represent the retinal vessel diameters of a person.

  • Computer‐assisted retinal vessel measurement in an older population: correlation between right and left eyes
    Clinical and Experimental Ophthalmology, 2003
    Co-Authors: Harry Leung, Jie Jin Wang, Elena Rochtchina, Tien Yin Wong, Larry D. Hubbard, Ronald Klein, Paul Mitchell

    Abstract:

    This study assessed the correlation between computer-assisted retinal vessel measurements of right and left eyes, from subjects in a defined, community-based older population. Retinal photographs from participants in the Blue Mountains Eye Study were digitized. All retinal Arterioles and venules located 0.5−1.0 disc diameters from the optic disc margin were identified and a computer program measured their diameters. Pearson correlation (R2) statistic was used to assess the correlation in a random subsample of 1546 images. Substantial correlation between right and left eye measurements was found for summary indices of retinal Arterioles (R2 = 0.70) and venules (R2 = 0.77). Higher correlation was found for intragrader (R2 0.75−079) than for intergrader assessment (R2 0.67−0.72). Moderate correlation was found in Arteriole-to-venule ratio assessed by the same (R2 = 0.57) or different (R2 = 0.52) graders. Measurements from one eye can thus adequately represent the retinal vessel diameters of a person.