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Functionally induced changes in water transport in the proximal tubule segment of rat kidneys.

Faarup P, Holstein-Rathlou NH, Nørgaard T, Harrison AP, Bastholm L, Thatt L, Johansen FF, Hegedüs V - Int J Nephrol Renovasc Dis (2011)

Bottom Line: However, in the second segment, a special cellular phenomenon was constantly present, comprising a significant intercellular space that was easily identified using a light microscope.In the third segment, in which the presence of basolateral interdigitations is minimal, the small lateral space, which was found to be present in cryopreparations between neighboring cells from the normal kidney, was found to be enlarged by heavy salt loading of short duration.It is concluded that these cryotechniques demonstrate quantitative structural variations between superficial and deep nephrons, as well as the presence of extracellular areas between the cells of the second and the third segment, representing a structural background for the essential transport of water from the proximal tubules to the peritubular capillaries.

View Article: PubMed Central - PubMed

Affiliation: Department of Biomedical Sciences, Panum Institute University of Copenhagen.

ABSTRACT
To eliminate freezing artifacts in the proximal tubule cells, two cryotechniques were applied to normal rat kidneys, ie, freeze substitution and special freeze drying. In addition, salt depletion and salt loading were applied to groups of rats to evaluate whether the segmental structure of the proximal tubule could be altered. In the superficial part of the renal cortex of normal kidneys, the typical first segment structure in the proximal tubule was generally present in the early postglomerular fraction of the tubule. However, in the second segment, a special cellular phenomenon was constantly present, comprising a significant intercellular space that was easily identified using a light microscope. In the third segment, in which the presence of basolateral interdigitations is minimal, the small lateral space, which was found to be present in cryopreparations between neighboring cells from the normal kidney, was found to be enlarged by heavy salt loading of short duration. It is concluded that these cryotechniques demonstrate quantitative structural variations between superficial and deep nephrons, as well as the presence of extracellular areas between the cells of the second and the third segment, representing a structural background for the essential transport of water from the proximal tubules to the peritubular capillaries.

No MeSH data available.


A PAS-stained freeze-substituted kidney, showing the superficial cortex from a rat that had been exposed to a heavy salt-loading of short duration (Group 2 C).Notes: Please note that the proximal tubular loop, descending from the glomerulus (X) has changed in structure from that of a S1 to a more typical S2-like cell. Note also, that the luminal diameter, the cellular- and brush border height, and the presence of basolateral spaces are somewhat identical to the structure of the surrounding S2 loops. The change in structure from S1 to S2 in the initial postglomerular fraction was more significant among superficial cf. juxtamedullar nephrons (Graph IA and IB). The scale bar represents 25 μm.
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f6-ijnrd-4-073: A PAS-stained freeze-substituted kidney, showing the superficial cortex from a rat that had been exposed to a heavy salt-loading of short duration (Group 2 C).Notes: Please note that the proximal tubular loop, descending from the glomerulus (X) has changed in structure from that of a S1 to a more typical S2-like cell. Note also, that the luminal diameter, the cellular- and brush border height, and the presence of basolateral spaces are somewhat identical to the structure of the surrounding S2 loops. The change in structure from S1 to S2 in the initial postglomerular fraction was more significant among superficial cf. juxtamedullar nephrons (Graph IA and IB). The scale bar represents 25 μm.

Mentions: The most important finding of our study with regard to normal kidney function has been the observation of a consistently open basolateral space between the interdigitating S2 segment cells of the proximal tubule, giving rise to an anastomosing, widely open, extracellular compartment for the transport of water (Figures 1–6). A parallel phenomenon of equal importance is an open lateral space between the cells in the S3 segment (Figure 7). In investigations of the normal rat kidney, in which a cryopreparation was omitted, no dilatation of the basolateral or lateral space between the cells of the proximal tubule was observed.16–19 The essential structural differences between the three cell types (S1, S2, and S3) in the proximal tubule, as seen in the cryopreparations of the renal cortex, are illustrated in Figure 10.


Functionally induced changes in water transport in the proximal tubule segment of rat kidneys.

Faarup P, Holstein-Rathlou NH, Nørgaard T, Harrison AP, Bastholm L, Thatt L, Johansen FF, Hegedüs V - Int J Nephrol Renovasc Dis (2011)

A PAS-stained freeze-substituted kidney, showing the superficial cortex from a rat that had been exposed to a heavy salt-loading of short duration (Group 2 C).Notes: Please note that the proximal tubular loop, descending from the glomerulus (X) has changed in structure from that of a S1 to a more typical S2-like cell. Note also, that the luminal diameter, the cellular- and brush border height, and the presence of basolateral spaces are somewhat identical to the structure of the surrounding S2 loops. The change in structure from S1 to S2 in the initial postglomerular fraction was more significant among superficial cf. juxtamedullar nephrons (Graph IA and IB). The scale bar represents 25 μm.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3108790&req=5

f6-ijnrd-4-073: A PAS-stained freeze-substituted kidney, showing the superficial cortex from a rat that had been exposed to a heavy salt-loading of short duration (Group 2 C).Notes: Please note that the proximal tubular loop, descending from the glomerulus (X) has changed in structure from that of a S1 to a more typical S2-like cell. Note also, that the luminal diameter, the cellular- and brush border height, and the presence of basolateral spaces are somewhat identical to the structure of the surrounding S2 loops. The change in structure from S1 to S2 in the initial postglomerular fraction was more significant among superficial cf. juxtamedullar nephrons (Graph IA and IB). The scale bar represents 25 μm.
Mentions: The most important finding of our study with regard to normal kidney function has been the observation of a consistently open basolateral space between the interdigitating S2 segment cells of the proximal tubule, giving rise to an anastomosing, widely open, extracellular compartment for the transport of water (Figures 1–6). A parallel phenomenon of equal importance is an open lateral space between the cells in the S3 segment (Figure 7). In investigations of the normal rat kidney, in which a cryopreparation was omitted, no dilatation of the basolateral or lateral space between the cells of the proximal tubule was observed.16–19 The essential structural differences between the three cell types (S1, S2, and S3) in the proximal tubule, as seen in the cryopreparations of the renal cortex, are illustrated in Figure 10.

Bottom Line: However, in the second segment, a special cellular phenomenon was constantly present, comprising a significant intercellular space that was easily identified using a light microscope.In the third segment, in which the presence of basolateral interdigitations is minimal, the small lateral space, which was found to be present in cryopreparations between neighboring cells from the normal kidney, was found to be enlarged by heavy salt loading of short duration.It is concluded that these cryotechniques demonstrate quantitative structural variations between superficial and deep nephrons, as well as the presence of extracellular areas between the cells of the second and the third segment, representing a structural background for the essential transport of water from the proximal tubules to the peritubular capillaries.

View Article: PubMed Central - PubMed

Affiliation: Department of Biomedical Sciences, Panum Institute University of Copenhagen.

ABSTRACT
To eliminate freezing artifacts in the proximal tubule cells, two cryotechniques were applied to normal rat kidneys, ie, freeze substitution and special freeze drying. In addition, salt depletion and salt loading were applied to groups of rats to evaluate whether the segmental structure of the proximal tubule could be altered. In the superficial part of the renal cortex of normal kidneys, the typical first segment structure in the proximal tubule was generally present in the early postglomerular fraction of the tubule. However, in the second segment, a special cellular phenomenon was constantly present, comprising a significant intercellular space that was easily identified using a light microscope. In the third segment, in which the presence of basolateral interdigitations is minimal, the small lateral space, which was found to be present in cryopreparations between neighboring cells from the normal kidney, was found to be enlarged by heavy salt loading of short duration. It is concluded that these cryotechniques demonstrate quantitative structural variations between superficial and deep nephrons, as well as the presence of extracellular areas between the cells of the second and the third segment, representing a structural background for the essential transport of water from the proximal tubules to the peritubular capillaries.

No MeSH data available.