Limits...
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.


Related in: MedlinePlus

Quantitative segmental evaluation of the immediate postglomerular fraction of the proximal convoluted tubule in freeze-substituted tissue from the renal cortex.Notes: 1A) Among the superficial nephrons from normal kidneys (Group 1A) the number of S1-like cells far exceeds that of the S1-2 like cells, which are themselves significantly more frequent than the S2-like cells. Moderate salt depletion or salt loading over a period of 1 month (Groups 2A and 2B) does not change the distribution significantly. However, a heavy salt loading of short duration (1 hour) (Group 2C) significantly reverses the frequencies of the S1, S1-2 and S2-like cells such that the presence of the S1-like structured cells falls far below the number of S1-2-like and S2-like cells in this part of the tubule. After a temporary, yet significant reversal of the structural changes in the S1- and S2-like structures some 48 hours later, the presence of both S1-, S1-2 and S2-like cells becomes nearly identical (see Groups 2D, E and F) 2 days, 2 weeks or 4 weeks after the acute intervention of the heavy salt loading. 1B) In the juxtamedullary located nephrons from freeze substituted normal kidneys the presence of both the S1-like, and the S2-like cells of the immediately postglomerular located fraction of the proximal convoluted tubule were lower in number than the S1-2 like cells (Group 1A). No significant changes were found during moderate salt depletion or salt loading(Groups 2A and B). After a heavy salt loading of short duration (Group 2C) the S1-like cells were nearly totally eliminated, and the S2-like cells were increased in number significantly, to subsequently comprise two thirds of the structure in this region. Interestingly, even 4 weeks later the Control Group (F) did not show any change in this distribution.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC3108790&req=5

f11-ijnrd-4-073: Quantitative segmental evaluation of the immediate postglomerular fraction of the proximal convoluted tubule in freeze-substituted tissue from the renal cortex.Notes: 1A) Among the superficial nephrons from normal kidneys (Group 1A) the number of S1-like cells far exceeds that of the S1-2 like cells, which are themselves significantly more frequent than the S2-like cells. Moderate salt depletion or salt loading over a period of 1 month (Groups 2A and 2B) does not change the distribution significantly. However, a heavy salt loading of short duration (1 hour) (Group 2C) significantly reverses the frequencies of the S1, S1-2 and S2-like cells such that the presence of the S1-like structured cells falls far below the number of S1-2-like and S2-like cells in this part of the tubule. After a temporary, yet significant reversal of the structural changes in the S1- and S2-like structures some 48 hours later, the presence of both S1-, S1-2 and S2-like cells becomes nearly identical (see Groups 2D, E and F) 2 days, 2 weeks or 4 weeks after the acute intervention of the heavy salt loading. 1B) In the juxtamedullary located nephrons from freeze substituted normal kidneys the presence of both the S1-like, and the S2-like cells of the immediately postglomerular located fraction of the proximal convoluted tubule were lower in number than the S1-2 like cells (Group 1A). No significant changes were found during moderate salt depletion or salt loading(Groups 2A and B). After a heavy salt loading of short duration (Group 2C) the S1-like cells were nearly totally eliminated, and the S2-like cells were increased in number significantly, to subsequently comprise two thirds of the structure in this region. Interestingly, even 4 weeks later the Control Group (F) did not show any change in this distribution.

Mentions: In terms of a quantitative analysis of the cells in the juxtamedullary region, ie, in the immediate postglomerular neck region of the normal kidney, the S1 segments were found to be significantly fewer in number than those measured superficially (see Graph 1A compared with Graph 1B, Group 1A). However, a total count of the convoluted proximal tubule showed a difference between superficial and juxtamedullary nephrons (significantly lower numbers of S1 segment loops) for the juxtamedullary nephrons alone (see Graph 2A compared with Graph 2B, Group 1A). In the vitally stained, freeze-dried specimens (free of fixation, water contamination, and embedding media artifact), a similar structure was observed to that of the freeze-substituted specimens with regard to the S1 and S2 loops (Figure 3).


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)

Quantitative segmental evaluation of the immediate postglomerular fraction of the proximal convoluted tubule in freeze-substituted tissue from the renal cortex.Notes: 1A) Among the superficial nephrons from normal kidneys (Group 1A) the number of S1-like cells far exceeds that of the S1-2 like cells, which are themselves significantly more frequent than the S2-like cells. Moderate salt depletion or salt loading over a period of 1 month (Groups 2A and 2B) does not change the distribution significantly. However, a heavy salt loading of short duration (1 hour) (Group 2C) significantly reverses the frequencies of the S1, S1-2 and S2-like cells such that the presence of the S1-like structured cells falls far below the number of S1-2-like and S2-like cells in this part of the tubule. After a temporary, yet significant reversal of the structural changes in the S1- and S2-like structures some 48 hours later, the presence of both S1-, S1-2 and S2-like cells becomes nearly identical (see Groups 2D, E and F) 2 days, 2 weeks or 4 weeks after the acute intervention of the heavy salt loading. 1B) In the juxtamedullary located nephrons from freeze substituted normal kidneys the presence of both the S1-like, and the S2-like cells of the immediately postglomerular located fraction of the proximal convoluted tubule were lower in number than the S1-2 like cells (Group 1A). No significant changes were found during moderate salt depletion or salt loading(Groups 2A and B). After a heavy salt loading of short duration (Group 2C) the S1-like cells were nearly totally eliminated, and the S2-like cells were increased in number significantly, to subsequently comprise two thirds of the structure in this region. Interestingly, even 4 weeks later the Control Group (F) did not show any change in this distribution.
© Copyright Policy
Related In: Results  -  Collection

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

f11-ijnrd-4-073: Quantitative segmental evaluation of the immediate postglomerular fraction of the proximal convoluted tubule in freeze-substituted tissue from the renal cortex.Notes: 1A) Among the superficial nephrons from normal kidneys (Group 1A) the number of S1-like cells far exceeds that of the S1-2 like cells, which are themselves significantly more frequent than the S2-like cells. Moderate salt depletion or salt loading over a period of 1 month (Groups 2A and 2B) does not change the distribution significantly. However, a heavy salt loading of short duration (1 hour) (Group 2C) significantly reverses the frequencies of the S1, S1-2 and S2-like cells such that the presence of the S1-like structured cells falls far below the number of S1-2-like and S2-like cells in this part of the tubule. After a temporary, yet significant reversal of the structural changes in the S1- and S2-like structures some 48 hours later, the presence of both S1-, S1-2 and S2-like cells becomes nearly identical (see Groups 2D, E and F) 2 days, 2 weeks or 4 weeks after the acute intervention of the heavy salt loading. 1B) In the juxtamedullary located nephrons from freeze substituted normal kidneys the presence of both the S1-like, and the S2-like cells of the immediately postglomerular located fraction of the proximal convoluted tubule were lower in number than the S1-2 like cells (Group 1A). No significant changes were found during moderate salt depletion or salt loading(Groups 2A and B). After a heavy salt loading of short duration (Group 2C) the S1-like cells were nearly totally eliminated, and the S2-like cells were increased in number significantly, to subsequently comprise two thirds of the structure in this region. Interestingly, even 4 weeks later the Control Group (F) did not show any change in this distribution.
Mentions: In terms of a quantitative analysis of the cells in the juxtamedullary region, ie, in the immediate postglomerular neck region of the normal kidney, the S1 segments were found to be significantly fewer in number than those measured superficially (see Graph 1A compared with Graph 1B, Group 1A). However, a total count of the convoluted proximal tubule showed a difference between superficial and juxtamedullary nephrons (significantly lower numbers of S1 segment loops) for the juxtamedullary nephrons alone (see Graph 2A compared with Graph 2B, Group 1A). In the vitally stained, freeze-dried specimens (free of fixation, water contamination, and embedding media artifact), a similar structure was observed to that of the freeze-substituted specimens with regard to the S1 and S2 loops (Figure 3).

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.


Related in: MedlinePlus