Organ Specificity and Functional Relevance of the Arterial Structure: A Comparative Study in the Kidney and the Skeletal Muscle with Electron Microscopy

Hosoyamada, Yasue; Ichimura, Koichiro; Sakai, Tatsuo

doi:10.1159/000442978

Cited by 5 publications

(5 citation statements)

References 19 publications

(24 reference statements)

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“…This may help to limit current drain into the media. 71 The presence of glycocalyx on the surface of ECs may also serve as an insulator at the luminal side of the endothelium. 72 Factors affecting the conductive pathway in the kidney are not well elucidated; a description of what is known was recently reviewed by Welsh et al 63 Computational-modeling studies of VCRs show endothelium-initiated conduction and parallel changes in membrane voltage occurring in VSMCs; however, these assume uniform axial MEGJ distribution, which is not the case.…”

Section: Connexinsmentioning

confidence: 99%

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Tubuloglomerular Feedback Synchronization in Nephrovascular Networks

Zehra

Cupples

Braam

2021

JASN

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To perform their functions, the kidneys maintain stable blood perfusion in the face of fluctuations in systemic BP. This is done through autoregulation of blood flow by the generic myogenic response and the kidney-specific tubuloglomerular feedback (TGF) mechanism. The central theme of this paper is that, to achieve autoregulation, nephrons do not work as single units to manage their individual blood flows, but rather communicate electrically over long distances to other nephrons via the vascular tree. Accordingly, we define the nephrovascular unit (NVU) to be a structure consisting of the nephron, glomerulus, afferent arteriole, and efferent arteriole. We discuss features that require and enable distributed autoregulation mediated by TGF across the kidney. These features include the highly variable topology of the renal vasculature which creates variability in circulation and the potential for mismatch between tubular oxygen demand and delivery; the self-sustained oscillations in each NVU arising from the autoregulatory mechanisms; and the presence of extensive gap junctions formed by connexins and their properties that enable long-distance transmission of TGF signals. The existence of TGF synchronization across the renal microvascular network enables an understanding of how NVUs optimize oxygenation-perfusion matching while preventing transmission of high systemic pressure to the glomeruli, which could lead to progressive glomerular and vascular injury.

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Section: Connexinsmentioning

confidence: 99%

“…This may help to limit current drain into the media. 71 The presence of glycocalyx on the surface of ECs may also serve as an insulator at the luminal side of the endothelium. 72…”

Section: Vascular Conducted Responses Enable Communication In the Art...mentioning

confidence: 99%

Tubuloglomerular Feedback Synchronization in Nephrovascular Networks

Zehra

Cupples

Braam

2021

JASN

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“…The structure of the vascular wall may affect both the local vasoconstriction and conduction properties. The vascular wall in renal vessels with a diameter <40 μm is thicker compared to vessels from skeletal muscles ( Hosoyamada et al, 2015 ), which would reduce conduction in afferent arterioles. In both KO strains, changes in wall trans-sectional area (WTA) and stress sensitivity in the afferent arteriole have been found ( Jacobsen and Sorensen, 2015 ; Møller et al, 2020 ).…”

Section: Discussionmentioning

confidence: 99%

Lack of Connexins 40 and 45 Reduces Local and Conducted Vasoconstrictor Responses in the Murine Afferent Arterioles

et al. 2020

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The juxtaglomerular apparatus (JGA) is an essential structure in the regulation of renal function. The JGA embodies two major functions: tubuloglomerular feedback (TGF) and renin secretion. TGF is one of the mechanisms mediating renal autoregulation. It is initiated by an increase in tubular NaCl concentration at the macula densa cells. This induces a local afferent arteriolar vasoconstriction and a conducted response that can be measured several 100 μm upstream from the juxtaglomerular segment. This spread of the vasomotor response into the surrounding vasculature likely plays a key role in renal autoregulation, and it requires the presence of gap junctions, intercellular pores based on connexin (Cx) proteins. Several Cx isoforms are expressed in the JGA and in the arteriolar wall. Disruption of this communication pathway is associated with reduced TGF, dysregulation of renin secretion, and hypertension. We examine if the absence of Cx40 or Cx45, expressed in the endothelial and vascular smooth muscle cells respectively, attenuates afferent arteriolar local and conducted vasoconstriction. Afferent arterioles from wildtype and Cx-deficient mice (Cx40 and Cx45) were studied using the isolated perfused juxtamedullary nephron preparation. Vasoconstriction was induced via electrical pulse stimulation at the glomerular entrance. Inner afferent arteriolar diameter was measured locally and upstream to evaluate conducted vasoconstriction. Electrical stimulation induced local vasoconstriction in all groups. The local vasoconstriction was significantly smaller when Cx40 was absent. The vasoconstriction decreased in magnitude with increasing distance from the stimulation site. In both Cx40 and Cx45 deficient mice, the vasoconstriction conducted a shorter distance along the vessel compared to wild-type mice. In Cx40 deficient arterioles, this may be caused by a smaller local vasoconstriction. Collectively, these findings imply that Cx40 and Cx45 are central for normal vascular reactivity and, therefore, likely play a key role in TGF-induced regulation of afferent arteriolar resistance.

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“…Among the staffs of the Department of Anatomy, Hidetake Kurihara (now, Aino University) studied the intercellular signals in the renal glomerulus 8) , and Miki Nagase (now, Kyorin University, Faculty of Medicine) studied effect of Rac1 macrophages to the inflammatory mechanisms in the kidney 9) . With Yukie Hosoyamada at the Chiba Prefectural University of Health Sciences, I studied the ultrastructure of various tissues including interstitial collagen fibers in the liver 10) , and in the intestinal villi 11) , and the structure of blood vessels in the kidney and skeletal muscles 12) (Figure-1).…”

Section: Research In the Microscopic Anatomymentioning

confidence: 99%

On the Human Body: Research, Literacy and Creativity

Sakai

2019

Juntendo Medical Journal

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In the microscopic research on the kidney, I discovered the mechanical function of mesangial cells to counterbalance the expanding force of blood pressure in 1987. Since then I studied the microscopic morphology of renal glomerulus, and of the interstitium and blood vessels in various tissues, 2) In the macroscopic research with my colleagues, I studied the morphology of the peripheral nerves and arteries. In recent years, the isolated muscle specimens became an excellent tool to analyze the functional architecture of skeletal muscles. 3) In the history of medicine, I studied especially the history of anatomy, of medical education and of Western medicine in general. 4) In the academic and social education of the anatomy and body donation, I have published many academic textbooks, including 17 titles and 35 editions of the translated and/or supervised textbooks of anatomy, 17 titles and 26 editions authored and/or edited textbooks of anatomy and biology. I have long been engaged in the activities of Tokushi Kaibo Zenkoku Rengokai [National Confederation of Anatomy Body Donation], and served the executive director from 2002 to 2006 and the chairman from 2006 to 2010. I experienced that the body donation became increasingly popular so that the proportion of donated cadavers to the total dissected ones increased from 42% in the 1983 to more than 99% in the 2018.

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Organ Specificity and Functional Relevance of the Arterial Structure: A Comparative Study in the Kidney and the Skeletal Muscle with Electron Microscopy

Cited by 5 publications

References 19 publications

Tubuloglomerular Feedback Synchronization in Nephrovascular Networks

Tubuloglomerular Feedback Synchronization in Nephrovascular Networks

Lack of Connexins 40 and 45 Reduces Local and Conducted Vasoconstrictor Responses in the Murine Afferent Arterioles

On the Human Body: Research, Literacy and Creativity

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