Ultrastructure of three-dimensionally localized distal nephron segments in superficial cortex of the rat kidney

Dørup, Jens

doi:10.1016/0889-1605(88)90052-3

Cited by 17 publications

(28 citation statements)

References 33 publications

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“…In particular, DCT2 contains TSC, characteristic of the DCT (19), but also expresses CaBK (20,27), which is characteristic of the CNT. In addition, intercalated cells are present between DCT2 cells (9,21). In our study, EFG immunoreactivity was found only in the DCT1 region and not in the DCT2 region, which expressed both TSC and CaBP.…”

Section: Discussioncontrasting

confidence: 44%

“…Previous studies have examined the immunoreactivity of EGF in the different segments without demonstrating a difference between DCT1 and DCT2 (25,31,(32)(33)(34). Dorup (9) reported ultrastructural distinctions between cells in the early and later part of the DCT in rat kidney. Loffing (19) proposed the subdivision of the DCT into DCT1 (sodium/calcium exchanger negative) and DCT2 (sodium/calcium exchanger positive).…”

Section: Discussionmentioning

confidence: 96%

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Expression of epidermal growth factor in the developing rat kidney

Jung¹,

Song²,

Li³

et al. 2005

American Journal of Physiology-Renal Physiology

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Epidermal growth factor (EGF) is important in mammalian renal development. In our study, we investigated the detailed distribution and the time of the first appearance of EGF in developing rat kidney. Kidneys from embryonic 18 (E18)- and 20-day-old (E20) fetuses, postnatal 1 (P1)-, 3 (P3)-, 7 (P7)-, 14 (P14)-, and 21-day-old (P21) pups, and adults were processed for immunohistochemistry and electronmicroscopy. In adult rat kidney, EGF immunoreactivity was found in distal tubule including the thick ascending limb (TAL) and portion 1 of distal convoluted tubule (DCT1), whereas no EGF immunoreactivity was seen in portion 2 of distal convoluted tubule (DCT2) and connecting tubule. In developing kidney, EGF-positive cells first appeared at P3 and were localized in the middle portion of the differentiating TAL of the corticomedullary junction. By P7, the abundance of EGF expression had dramatically increased in the medullary TAL. Between P14 and P21, EGF immunoreactivity was found in the TAL and the DCT for the first time. However, EGF-positive and EGF-negative cells were in the TAL in developing rat kidney. EGF-positive cells did not differ from negative cells in the expression of sodium transport proteins or in the proliferation rate at P3 and P7. In the TAL, smooth-surfaced cells had strong EGF immunoreactivity, but no EGF immunoreactivity was seen in the rough-surfaced cells with well-developed microvilli. Our results suggest that the expression of EGF in developing kidney plays an important role in the regulation of growth and differentiation of the loop of Henle during kidney development and that this may act in the paracrine mode.

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Section: Discussioncontrasting

confidence: 44%

Section: Discussionmentioning

confidence: 96%

Expression of epidermal growth factor in the developing rat kidney

Jung¹,

Song²,

Li³

et al. 2005

American Journal of Physiology-Renal Physiology

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“…We therefore used an average value of 1 mm. We again use measured values of 516 cells/mm and assume that two-thirds are principal or CNT cells (3). Using the same value of Ϫ80 mV for the apical membrane potential, each cell has a higher transport rate of 1,180 pA/cell for an overall transport rate of 30.4 mA, or 19 mol/min.…”

Section: Discussionmentioning

confidence: 99%

“…However, we avoided putative intercalated cells, recognized as with the CCT by a surface that appeared to be raised above the plane of the flattened tubule. The data presented here presumably reflect a combination of principal and CNT cells, which together comprise about two-thirds of the total in this segment (3).…”

Section: Animalsmentioning

confidence: 95%

Na channels in the rat connecting tubule

Frindt

Palmer

2004

American Journal of Physiology-Renal Physiology

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Epithelial Na channels were investigated using patch-clamp techniques in connecting tubule (CNT) segments isolated from rat kidney. Cell-attached patches with Li+ in the patch pipette contained channels with conductances for inward currents of 13-16 pS and slow opening and closing kinetics, similar to properties of Na channels in the cortical collecting tubule (CCT). Macroscopic amiloride-sensitive currents (INa) were also observed under whole cell clamp conditions. These currents were undetectable in cells from control rats but were large when the animals were infused with aldosterone (1,380+/-340 pA/cell at a holding potential of -100 mV) or fed a high-K diet (670+/-260 pA/cell) for 1 wk. Under both of these conditions, currents in cells of the CNT were two- to fourfold larger than currents in cells of the CCT of the same animals. In aldosterone-treated animals, currents in cells of the initial collecting tubule (iCT) were intermediate, such that the relative magnitude of INa was as follows: CNT > iCT > CCT. Quantitative analysis of the results suggests that the maximal capacity of the aggregate population of CNTs to reabsorb Na could be as high as 18 micromol/min, or approximately 10% of the filtered load of Na. This capacity is approximately 10 times higher than that of the CCT.

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“…The length of this post macula densa segment varies greatly. It is 0–500 μm in rabbits and 150 ± 20 μm in rats (105). This segment never reaches the kidney surface in normal rats, rabbits, or humans (254).…”

Section: Definition and Morphologymentioning

confidence: 99%