Renal tubule of dogfish, Scyliorhinus caniculus: A comprehensive study of structure with emphasis on intramembrane particles and immunoreactivity for H+‐K+‐adenosine triphosphatase

Hentschel, H.; Mahler, Stephen M.; Herter, Peter; Elger, Marlies

doi:10.1002/ar.1092350404

Cited by 19 publications

(9 citation statements)

References 40 publications

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“…However, the CT was recognizable because the apical membrane was strongly stained by PAS (Fig. 2b), presumably due to the existence of small vesicles beneath the apical membrane (Hentschel et al 1993). The CT did not make a loop, but passed through the bundle and connected to the collecting duct (CD) near the bundle tip (Fig.…”

Section: Distal Segment Collecting Tubule and Collecting Ductmentioning

confidence: 96%

Morphological and molecular investigations of the holocephalan elephant fish nephron: the existence of a countercurrent-like configuration and two separate diluting segments in the distal tubule

et al. 2015

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In marine cartilaginous fish, reabsorption of filtered urea by the kidney is essential for retaining a large amount of urea in their body. However, the mechanism for urea reabsorption is poorly understood due to the complexity of the kidney. To address this problem, we focused on elephant fish (Callorhinchus milii) for which a genome database is available, and conducted molecular mapping of membrane transporters along the different segments of the nephron. Basically, the nephron architecture of elephant fish was similar to that described for elasmobranch nephrons, but some unique features were observed. The late distal tubule (LDT), which corresponded to the fourth loop of the nephron, ran straight near the renal corpuscle, while it was convoluted around the tip of the loop. The ascending and descending limbs of the straight portion were closely apposed to each other and were arranged in a countercurrent fashion. The convoluted portion of LDT was tightly packed and enveloped by the larger convolution of the second loop that originated from the same renal corpuscle. In situ hybridization analysis demonstrated that co-localization of Na(+),K(+),2Cl(-) cotransporter 2 and Na(+)/K(+)-ATPase α1 subunit was observed in the early distal tubule and the posterior part of LDT, indicating the existence of two separate diluting segments. The diluting segments most likely facilitate NaCl absorption and thereby water reabsorption to elevate urea concentration in the filtrate, and subsequently contribute to efficient urea reabsorption in the final segment of the nephron, the collecting tubule, where urea transporter-1 was intensely localized.

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Section: Distal Segment Collecting Tubule and Collecting Ductmentioning

confidence: 96%

Morphological and molecular investigations of the holocephalan elephant fish nephron: the existence of a countercurrent-like configuration and two separate diluting segments in the distal tubule

et al. 2015

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“…In particular, the basolateral membranes of the early distal tubule and the late distal tubule and the apical membrane of the collecting duct were intensely stained (108). Hentschel et al (45) examined in lesser spotted dogfish, using a different antibody raised against an extracytoplasmic domain peptide of the rat H ϩ -K ϩ -ATPase. They found immunoreaction in the apical membranes of the proximal segments and the late distal tubule.…”

Section: Urea Synthesis In the Kidneymentioning

confidence: 99%

Morphological and functional characteristics of the kidney of cartilaginous fishes: with special reference to urea reabsorption

Hyodo

Kakumura

Takagi

et al. 2014

American Journal of Physiology-Regulatory, Integrative and Comp

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functional characteristics of the kidney of cartilaginous fishes: with special reference to urea reabsorption. Am J Physiol Regul Integr Comp Physiol 307: R1381-R1395, 2014. First published October 22, 2014 doi:10.1152/ajpregu.00033.2014.-For adaptation to highsalinity marine environments, cartilaginous fishes (sharks, skates, rays, and chimaeras) adopt a unique urea-based osmoregulation strategy. Their kidneys reabsorb nearly all filtered urea from the primary urine, and this is an essential component of urea retention in their body fluid. Anatomical investigations have revealed the extraordinarily elaborate nephron system in the kidney of cartilaginous fishes, e.g., the four-loop configuration of each nephron, the occurrence of distinct sinus and bundle zones, and the sac-like peritubular sheath in the bundle zone, in which the nephron segments are arranged in a countercurrent fashion. These anatomical and morphological characteristics have been considered to be important for urea reabsorption; however, a mechanism for urea reabsorption is still largely unknown. This review focuses on recent progress in the identification and mapping of various pumps, channels, and transporters on the nephron segments in the kidney of cartilaginous fishes. The molecules include urea transporters, Na, and aquaporins, which most probably all contribute to the urea reabsorption process. Although research is still in progress, a possible model for urea reabsorption in the kidney of cartilaginous fishes is discussed based on the anatomical features of nephron segments and vascular systems and on the results of molecular mapping. The molecular anatomical approach thus provides a powerful tool for understanding the physiological processes that take place in the highly elaborate kidney of cartilaginous fishes. cartilaginous fish; kidney; osmoregulation; transporters; urea BODY FLUID REGULATION is essential for all organisms to survive in their respective habitats, including freshwater (FW), seawater (SW), and terrestrial environments. It is well known that teleost fish regulate their plasma Na ϩ and Cl Ϫ concentrations and osmolality at levels about one-third of SW. Meanwhile, cartilaginous fishes (sharks, skates, rays, and chimaeras) have adopted a unique osmoregulatory strategy for adaptation to the high-salinity marine environment. Cartilaginous fishes control plasma ions to levels approximately one-half of surrounding SW while they store high concentrations of the nitrogenous compound urea as an osmolyte (the so-called "ureosmotic strategy"). As a result, their body fluids are slightly hyperosmotic to surrounding SW (for instance, plasma osmolality of houndshark is 1,000 mosmol/kg H 2 O in SW of 988 mosmol/kg H 2 O; Ref. 53), and thus cartilaginous fishes do not typically suffer dehydration even in the high-osmolality SW environment. To maintain high concentration of urea in the body, urea production by the ornithine urea cycle (OUC) is essential. Investigations on the OUC enzymes have proved that the liver is the primary organ f...

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“…Meanwhile, molecular anatomy can determine the localization of transport proteins for urea, ions and water in situ, and thus is a powerful tool to overcome the difficulty in studying the elasmobranch kidney. Spatial patterns in the distribution of various pumps (Hentschel et al, 1993;Swenson et al, 1994), channels and transporters (Biemesderfer et al, 1996) in the nephron segments can provide valuable information on the movement of the above molecules across the kidney tubules, and thus on the reabsorption mechanism of urea.…”

mentioning

confidence: 99%

A facilitative urea transporter is localized in the renal collecting tubule of the dogfishTriakis scyllia

Hyodo

Katoh

Kaneko

et al. 2004

Journal of Experimental Biology

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SUMMARYReabsorption of filtered urea by the kidney tubule is essential for retaining high levels of urea in body fluids of marine elasmobranchs. To elucidate the mechanisms of urea reabsorption, we examined the distribution of a facilitative urea transporter (UT) in the kidney of the dogfish Triakis scyllia. We isolated a cDNA encoding a UT that is homologous to the facilitative UT cloned from another dogfish species, Squalus acanthias. The Triakis UT mRNA is abundantly expressed in the kidney, while low levels of expression were detected in the brain and liver. In the dogfish kidney, each nephron makes four turns and traverses repeatedly between bundle zone and sinus zone. In the bundle zone, the resulting five tubular segments are arranged in a countercurrent loop fashion. Immunohistochemistry using specific antibodies raised against the cloned UT revealed that, among the nephron segments, the UT is expressed exclusively in the final segment of the bundle zone, i.e. in the collecting tubule of the Triakis kidney. In contrast to the limited localization of UT, the transport enzyme Na+/K+-ATPase is distributed in the basolateral membrane of numerous tubular segments both in the sinus zone and the bundle zone. However, in the collecting tubule,Na+/K+-ATPase immunoreactivity was not detected. The present study suggests that the collecting tubule is responsible for the reabsorption of urea in the marine elasmobranch kidney. Other countercurrent segments may contribute to production of a driving force for facilitative diffusion of urea through the UT.

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Renal tubule of dogfish, Scyliorhinus caniculus: A comprehensive study of structure with emphasis on intramembrane particles and immunoreactivity for H⁺‐K⁺‐adenosine triphosphatase

Cited by 19 publications

References 40 publications

Morphological and molecular investigations of the holocephalan elephant fish nephron: the existence of a countercurrent-like configuration and two separate diluting segments in the distal tubule

Morphological and molecular investigations of the holocephalan elephant fish nephron: the existence of a countercurrent-like configuration and two separate diluting segments in the distal tubule

Morphological and functional characteristics of the kidney of cartilaginous fishes: with special reference to urea reabsorption

A facilitative urea transporter is localized in the renal collecting tubule of the dogfishTriakis scyllia

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