Expression of aquaporins in the renal connecting tubule

2000 ◽  
Vol 279 (5) ◽  
pp. F874-F883 ◽  
Author(s):  
Richard A. Coleman ◽  
Daniel C. Wu ◽  
Jie Liu ◽  
James B. Wade
Keyword(s):  
Electron Microscopy ◽  
Quantitative Analysis ◽  
Collecting Duct ◽  
Immunogold Labeling ◽  
Low Permeability ◽  
Brattleboro Rats ◽  
Cortical Collecting Duct ◽  
Connecting Tubule ◽  
Tubule Cells ◽  
Late Region

The renal connecting tubule (CNT) is a distinct segment that occurs between the distal convoluted tubule (DCT) and the cortical collecting duct. On the basis of its characterization in rabbit it is widely believed that connecting tubule cells have a low permeability to water and do not respond to vasopressin. Here we utilize segment-specific markers and specific aquaporin antibodies to characterize expression of water channels in CNT of the rat by immunocytochemistry. Colocalization of aquaporin 2 (AQP2), AQP3, and AQP4 with Na+, Ca2+ exchanger (NCX), a transporter characteristic of the connecting tubule, gave heterogeneous labeling. There was aquaporin labeling in many but not all regions labeled by NCX. Colocalization of AQP2 with AQP3 and with AQP4 showed that AQP3 and AQP4 labeling were always accompanied by AQP2. Immunogold labeling and electron microscopy showed that NCX-labeled cells with AQP2 labeling had the morphology of CNT cells, whereas NCX-labeled cells without AQP2 labeling were DCT cells. The latter regions were identified as the late region of the DCT known as DCT2. Additionally, regions of CNT lacking AQP2 labeling could be identified in Brattleboro rats not treated with vasopressin but not in such animals chronically treated with deamino-Cys1,d-Arg8-vasopressin (dDAVP). Quantitative analysis of labeling was consistent with expression of AQP2 over a longer region of CNT after dDAVP exposure.

scholarly journals Localization of Inward Rectifier Potassium Channel Kir7.1 in the Basolateral Membrane of Distal Nephron and Collecting Duct

2000 ◽  
Vol 11 (11) ◽  
pp. 1987-1994
Author(s):  
KAYOKO OOKATA ◽  
AKIHIRO TOJO ◽  
YOSHIRO SUZUKI ◽  
NOBUHIRO NAKAMURA ◽  
KENJIRO KIMURA ◽  
...  
Keyword(s):  
Potassium Channel ◽  
Collecting Duct ◽  
Basolateral Membrane ◽  
Inward Rectifier ◽  
Kidney Cortex ◽  
Thick Ascending Limb ◽  
Cortical Collecting Duct ◽  
Distal Nephron ◽  
Connecting Tubule ◽  
Low K

Abstract. Inward rectifier potassium channels (Kir) play an important role in the K+ secretion from the kidney. Recently, a new subfamily of Kir, Kir7.1, has been cloned and shown to be present in the kidney as well as in the brain, choroid plexus, thyroid, and intestine. Its cellular and subcellular localization was examined along the renal tubule. Western blot from the kidney cortex showed a single band for Kir7.1 at 52 kD, which was also observed in microdissected segments from the thick ascending limb of Henle, distal convoluted tubule (DCT), connecting tubule, and cortical and medullary collecting ducts. Kir7.1 immunoreactivity was detected predominantly in the DCT, connecting tubule, and cortical collecting duct, with lesser expression in the thick ascending limb of Henle and in the medullary collecting duct. Kir7.1 was detected by electron microscopic immunocytochemistry on the basolateral membrane of the DCT and the principal cells of cortical collecting duct, but neither type A nor type B intercalated cells were stained. The message levels and immunoreactivity were decreased under low-K diet and reversed by low-K diet supplemented with 4% KCl. By the double-labeling immunogold method, both Kir7.1 and Na+, K+-ATPase were independently located on the basolateral membrane. In conclusion, the novel Kir7.1 potassium channel is located predominantly in the basolateral membrane of the distal nephron and collecting duct where it could function together with Na+, K+-ATPase and contribute to cell ion homeostasis and tubular K+ secretion.

scholarly journals Moxonidine inhibits Na+/H+ exchange in proximal tubule cells and cortical collecting duct

1997 ◽  
Vol 52 (2) ◽  
pp. 454-459 ◽  
Author(s):  
Eberhard Schlatter ◽  
Ieva Ankorina-Stark ◽  
Sabine Haxelmans ◽  
Helge Hohage
Keyword(s):  
Proximal Tubule ◽  
Collecting Duct ◽  
Cortical Collecting Duct ◽  
Proximal Tubule Cells ◽  
Tubule Cells

Similar chloride channels in the connecting tubule and cortical collecting duct of the mouse kidney

2006 ◽  
Vol 290 (6) ◽  
pp. F1421-F1429 ◽  
Author(s):  
Antoine Nissant ◽  
Marc Paulais ◽  
Sahran Lachheb ◽  
Stéphane Lourdel ◽  
Jacques Teulon
Keyword(s):  
Chloride Channels ◽  
Collecting Duct ◽  
Basolateral Membrane ◽  
Reversal Potential ◽  
Cell Types ◽  
Cortical Collecting Duct ◽  
Patch Clamp Technique ◽  
Connecting Tubule ◽  
Recording Conditions ◽  
Rich Solution

Using the patch-clamp technique, we investigated Cl− channels on the basolateral membrane of the connecting tubule (CNT) and cortical collecting duct (CCD). We found a ∼10-pS channel in CNT cell-attached patches. Substitution of sodium gluconate for NaCl in the pipette shifted the reversal potential by +25 mV, whereas N-methyl-d-gluconate chloride had no effect, indicating anion selectivity. On inside-out patches, we determined a selectivity sequence of Cl− > Br− ∼ NO3− > F−, which is compatible with that of ClC-K2, a Cl− channel in the distal nephron. In addition, the number of open channels ( NPo) measured in cell-attached patches was significantly increased when Ca2+ concentration or pH in the pipette was increased, which is another characteristic of ClC-K. These findings suggest that the basis for this channel is ClC-K2. A similar Cl− channel was found in CCD patches. Because CNT and CCD are heterogeneous tissues, we studied the cellular distribution of the Cl− channel using recording conditions (KCl-rich solution in the pipette) that allowed us to detect simultaneously Cl− channels and inwardly rectifying K+ channels. We detected Cl− channels alone in 45% and 42% and K+ channels alone in 51% and 58% of CNT and CCD patches, respectively. Cl− and K+ channels were recorded simultaneously from two patches (4% of patches) in the CNT and from none of the patches in the CCD. This indicates that Cl− and K+ channels are located in different cell types, which we suggest may be the intercalated cells and principal cells, respectively.

High baseline ROMK activity in mouse late distal convoluted and early connecting tubule (DCT2/CNT) probably contributes to aldosterone-independent K+ secretion

2021 ◽  
Author(s):  
Viatcheslav Nesterov ◽  
Marko Bertog ◽  
Christoph Korbmacher
Keyword(s):  
Single Channel ◽  
Apical Membrane ◽  
Collecting Duct ◽  
Standard Diet ◽  
Cortical Collecting Duct ◽  
Channel Activity ◽  
Connecting Tubule ◽  
Low Potassium ◽  
K Secretion ◽  
Baseline Conditions

The renal outer medullary K+ channel (ROMK) is co-localized with the epithelial Na+ channel (ENaC) in late distal convoluted tubule (DCT2), connecting tubule (CNT) and cortical collecting duct (CCD). ENaC-mediated Na+ absorption generates the electrical driving force for ROMK-mediated tubular K+ secretion which is critically important for maintaining renal K+ homeostasis. ENaC activity is aldosterone-dependent in late CNT and early CCD (CNT/CCD) but aldosterone-independent in DCT2 and early CNT (DCT2/CNT). This suggests that under baseline conditions with low plasma aldosterone ROMK-mediated K+ secretion mainly occurs in DCT2/CNT. Therefore, we hypothesized that baseline ROMK activity is higher in DCT2/CNT than in CNT/CCD. To test this hypothesis, patch-clamp experiments were performed in DCT2/CNT and CNT/CCD microdissected from mice maintained on standard diet. In single-channel recordings from outside-out patches we detected typical ROMK channel activity in both DCT2/CNT and CNT/CCD and confirmed that ROMK is the predominant K+ channel in the apical membrane. Amiloride-sensitive (ΔIami) and tertiapin-sensitive (ΔITPNQ) whole-cell currents were determined to assess ENaC and ROMK activity, respectively. As expected, baseline ΔIami was high in DCT2/CNT (~370 pA) but low in CNT/CCD (~60 pA). Importantly, ΔITPNQ was significantly higher in DCT2/CNT than in CNT/CCD (~810 pA versus ~350 pA). We conclude that high ROMK activity in DCT2/CNT is critical for aldosterone-independent renal K+ secretion under baseline conditions. A low potassium diet significantly reduced ENaC but not ROMK activity in DCT2/CNT. This suggests that modifying ENaC activity in DCT2/CNT plays a key regulatory role in adjusting renal K+ excretion to dietary K+ intake.

Expression of protein kinase C isoenzymes α, βI, and δ in subtypes of intercalated cells of mouse kidney

2006 ◽  
Vol 291 (5) ◽  
pp. F1052-F1060 ◽  
Author(s):  
Wan-Young Kim ◽  
Joon-Ho Jung ◽  
Eun-Young Park ◽  
Chul-Woo Yang ◽  
Hyang Kim ◽  
...  
Keyword(s):  
Collecting Duct ◽  
Apical Part ◽  
Mouse Kidney ◽  
Intercalated Cells ◽  
Principal Cells ◽  
Connecting Tubule ◽  
Intercalated Cell ◽  
Tubule Cells ◽  
Pkc Β ◽  
Calbindin D

Recent studies of the distribution of PKC isoenzymes in the mouse kidney demonstrated that PKC-α, -βI, and -δ are expressed in intercalated cells. The purpose of this study was to identify the intercalated cell subtypes that express the different PKC isoenzymes and determine the location of the PKC isoenzymes within these cells. Adult C57BL/6 mice kidney tissues were processed for multiple-labeling immunohistochemistry. Antibodies against the vacuolar H+-ATPase and pendrin were used to identify intercalated cell subtypes, whereas antibodies against calbindin D28K and aquaporin-2 (AQP2) were used to identify connecting tubule cells and principal cells of the collecting duct, respectively. Within type A intercalated cells, PKC-δ was highly expressed in the apical part of the cells, whereas immunoreactivity for both PKC-α and PKC-βI was weak. Type B intercalated cells exhibited strong expression of PKC-α, -βI, and -δ. PKC-α and -βI were localized throughout the cytoplasm, whereas PKC-δ was restricted to the basal domain. Within non-A-non-B cells, immunoreactivity for both PKC-α and PKC-βI was high in intensity and localized diffusely in the cytoplasm, whereas PKC-δ was localized in the apical part of the cells. None of the PKC isoenzymes (PKC-α, -βI, or -δ) were expressed in the calbindin D28K-positive connecting tubule cells. Within AQP2-positive principal cells of the collecting duct, PKC-α was expressed on the basolateral plasma membrane, but no significant staining was detected for PKC-βI and -δ. In summary, this study demonstrates distinct and differential expression patterns of PKC-α, -βI, and -δ in the three subtypes of intercalated cells in the mouse kidney.

Effect of glandular kallikrein on distal nephron HCO 3 − secretion in rats and on HCO 3 − secretion in MDCK cells

1997 ◽  
Vol 273 (5) ◽  
pp. F807-F816 ◽  
Author(s):  
P. Vallés ◽  
S. Ebner ◽  
W. Manucha ◽  
L. Gutierrez ◽  
M. Marin-Grez
Keyword(s):  
Electron Microscopy ◽  
Mdck Cells ◽  
Collecting Duct ◽  
Bathing Solution ◽  
Bicarbonate Secretion ◽  
Cortical Collecting Duct ◽  
Distal Nephron ◽  
Glandular Kallikrein ◽  
Renal Kallikrein ◽  
Kallikrein Activity

Renal kallikrein is localized in the connecting tubule cells and secreted into the tubular fluid at late distal nephron segments. The present experiments were performed to further test the hypothesis that renal kallikrein reduces bicarbonate secretion of cortical collecting duct (CCD). The effect of orthograde injections of pig pancreatic kallikrein (1 or 3 μg/ml) into the renal tubular system was investigated. Urine fractions (Fr) were collected after a 2-min stop flow. Changes in the urine fraction with respect to those in free-flow urine samples (Ff) were related to the respective polyfructosan (Inutest) ratio. Renal kallikrein activity (Fr:Ff kallikrein/Fr:Ff polyfructosan) increased significantly in the first two urine fractions collected after glandular kallikrein administration (kallikrein, 1 μg/ml, P < 0.05; kallikrein, 3 μg/ml, P < 0.01).[Formula: see text] secretion of collecting ducts was significantly reduced dose dependently by orthograde and also reduced by retrograde pig pancreatic kallikrein administration. Release of kinins into the fractions was not affected by the retrograde kallikrein injection, even though the kallikrein activity increased considerably (2.26 ± 0.2 vs. 1.55 ± 0.2, P < 0.05). Adequacy of retrograde injections for delivering substances to the CCD was demonstrated by injecting colloidal mercury and detecting the appearance of this mercury in the renal cortex by transmission electron microscopy. The integrity of the renal tissue after a retrograde ureteral injection was confirmed by scanning electron microscopy. These results confirm and extend previous data (M. Marin-Grez and P. Vallés. Renal Physiol. Biochem. 17: 301–306, 1994; and M. Marin-Grez, P. Vallés, and P. Odigie. J. Physiol. 488: 163–170, 1995) showing that renal kallikrein reduces bicarbonate secretion at the CCD, probably by inhibiting [Formula: see text]transported by a mechanism unrelated to its kininogenase activity. Support for this assessment was obtained in experiments testing the effect of kallikrein on the luminal bicarbonate secretion of a subpopulation of Madin-Darby canine kidney cells capable of extruding the anion. Kallikrein inhibited[Formula: see text]/Cl−exchange, and the degree of inhibition was dose dependent. This inhibition occurred in the absence of kininogen in the bathing solution.

Effect of acute respiratory acidosis on two populations of intercalated cells in rat cortical collecting duct

1987 ◽  
Vol 253 (6) ◽  
pp. F1142-F1156 ◽  
Author(s):  
J. W. Verlander ◽  
K. M. Madsen ◽  
C. C. Tisher
Keyword(s):  
Electron Microscopy ◽  
Collecting Duct ◽  
Respiratory Acidosis ◽  
Type A ◽  
Hydrogen Ion ◽  
Intercalated Cells ◽  
Cortical Collecting Duct ◽  
Type B ◽  
A Cells ◽  
Two Populations

Recent studies suggest the presence of two populations of intercalated cells in the rabbit cortical collecting duct (CCD), one involved with hydrogen ion secretion and another that may play a role in bicarbonate secretion. The purpose of this study was to determine whether two populations of intercalated cells are present in the rat CCD and to establish their response to acute respiratory acidosis. Rats were studied during normal acid-base conditions and after 4-5 h of respiratory acidosis. In all animals light microscopy and transmission and scanning electron microscopy revealed two configurations of intercalated cells, type A with an extensive apical tubulovesicular membrane compartment and prominent surface microprojections and type B with a well-developed vesicular compartment and short sparse surface microprojections. By transmission electron microscopy, studs were present on the cytoplasmic face of the apical plasmalemma and tubulovesicular profiles of A cells. In respiratory acidosis there was a striking increase in apical microprojections and in the surface density of the apical membrane of type A cells similar to the response observed previously in intercalated cells in the outer medullary collecting duct (OMCD) studied under the same physiological conditions. No changes were observed in type B cells. Scanning electron microscopy revealed no change in the relative number of type A and type B cells in respiratory acidosis. We conclude that two distinct populations of intercalated cells exist in the rat CCD: type A, which resembles the intercalated cells in the OMCD, and type B. The response of type A cells to acute respiratory acidosis and the similarity between these cells and intercalated cells in the OMCD, which are believed to secrete hydrogen ion, suggest that the type A cells are involved in hydrogen ion secretion in the CCD.

scholarly journals Hormonal regulation of phospholipase D activity in Ca2+ transporting cells of rabbit connecting tubule and cortical collecting duct

2001 ◽  
Vol 1538 (2-3) ◽  
pp. 329-338 ◽  
Author(s):  
Remko R. Bosch ◽  
Joost G.J. Hoenderop ◽  
Linda van der Heijden ◽  
Jan Joep H.H.M. De Pont ◽  
René J.M. Bindels ◽  
...  
Keyword(s):  
Phospholipase D ◽  
Hormonal Regulation ◽  
Collecting Duct ◽  
Cortical Collecting Duct ◽  
Connecting Tubule
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