Expression of mRNAs for different types of IP3 receptors in rat kidneys

1995 ◽  
Vol 268 (6) ◽  
pp. F1046-F1052 ◽  
Author(s):  
T. Yang ◽  
Y. Terada ◽  
H. Nonoguchi ◽  
K. Tomita ◽  
F. Marumo
Keyword(s):  
Collecting Duct ◽  
Rat Kidney ◽  
Ip3 Receptors ◽  
Ip3 Receptor ◽  
Receptor Mrna ◽  
Collecting Ducts ◽  
Different Types ◽  
Medullary Collecting Duct

Cloning studies have extensively characterized two types of inositol 1,4,5-trisphosphate (IP3) receptors from the rat. An IP3 receptor from the cerebellum is referred to as type 1, and a second, recently described, receptor is referred to as the type 2 IP3 receptor. The significance of different types of IP3 receptors, especially in vivo in the kidney, is not fully understood. We investigated the localization of mRNAs encoding these two types of IP3 receptors in microdissected nephron segments of rats using reverse transcription and polymerase chain reaction (RT-PCR) followed by Southern blot analysis. Type 1 IP3 receptor mRNA displayed a widespread, although not uniform, distribution along the nephron. In contrast, type 2 IP3 receptor mRNA was confined almost exclusively to collecting ducts, suggesting specific expression of type 2 IP3 receptor in collecting ducts. We then detected mRNAs for the two types of IP3 receptors in collecting ducts in dehydrated rats. Dehydration downregulated type 2 IP3 receptor mRNA in cortical collecting duct, outer medullary collecting duct, and the initial part of inner medullary collecting duct (IMCD), but not in the terminal part of IMCD. It had no effect on type 1 IP3 receptor mRNA expression in collecting ducts. We propose that different types of IP3 receptors may have different functions in the rat kidney. the initial part of inner medullary collecting duct (IMCD), but not in the terminal part of IMCD. It had no effect on type 1 IP3 receptor mRNA expression in collecting ducts. We propose that different types of IP3 receptors may have different functions in the rat kidney.

Increased collecting duct urea transporter expression in Dahl salt-sensitive rats

2003 ◽  
Vol 285 (1) ◽  
pp. F143-F151 ◽  
Author(s):  
Robert A. Fenton ◽  
Chung-Lin Chou ◽  
Shana Ageloff ◽  
William Brandt ◽  
John B. Stokes ◽  
...  
Keyword(s):  
Collecting Duct ◽  
Hydroxysteroid Dehydrogenase ◽  
Plasma Corticosterone ◽  
Urea Transporter ◽  
Rt Pcr ◽  
Collecting Ducts ◽  
Medullary Collecting Duct ◽  
Transporter Expression ◽  
Solute Transporter

Because abnormalities of inner medullary function have been proposed in Dahl salt-sensitive (DS) rats vs. salt-resistant (DR) rats, we performed transporter profiling by semiquantitative immunoblotting to determine whether specific solute transporter abundances are altered in inner medullas of DS rats vs. DR rats. Although none of the expressed Na transporters were upregulated in the inner medullas of DS rats compared with DR rats, there were marked increases in the protein abundances of the collecting duct urea transporters UT-A1 (to 212% of DR) and UT-A3 (to 223% of DR). These differences were confirmed by immunocytochemistry. Quantitative real-time RT-PCR showed higher mRNA abundance in DS rats for both UT-A1 (to 256% of DR) and UT-A3 (to 210% of DR). In isolated, perfused inner medullary collecting ducts, urea permeability was significantly greater in DS rats. Because both UT-A1 and UT-A3 are transcriptionally regulated by glucocorticoids, we measured both plasma corticosterone levels and inner medullary 11β-hydroxysteroid dehydrogenase type 2 (11β-HSD2) abundances. Although the plasma corticosterone concentrations were not different between DS and DR rats, immunoblotting and immunocytochemistry revealed a marked elevation of 11β-HSD2 abundance in DS rats. Consistent with the view that an elevated 11β-HSD2 level is responsible for increased urea transporter expression in the inner medullary collecting duct, administration of the 11β-HSD2 inhibitor carbenoxolone to DS rats decreased the abundances of UT-A1 and UT-A3 to levels similar to those seen in DR rats.

Lack of effect of atrial natriuretic peptide and urodilatin on vasopressin-stimulated cyclic AMP production in microdissected rat inner medullary collecting ducts

1994 ◽  
Vol 12 (2) ◽  
pp. 149-154
Author(s):  
W J Burgess ◽  
M N Perrott ◽  
R J Balment
Keyword(s):  
Cyclic Amp ◽  
Atrial Natriuretic Peptide ◽  
Natriuretic Peptide ◽  
Collecting Duct ◽  
Rat Kidney ◽  
Absolute Magnitude ◽  
Camp Production ◽  
Collecting Ducts ◽  
Medullary Collecting Duct ◽  
Atrial Natriuretic

ABSTRACT It is unclear whether the diuretic effects of atrial natriuretic peptide (ANP) result, in part, from an inhibition of the renal actions of vasopressin. Moreover, accruing evidence suggests that the kidneys themselves may produce an ANP-like peptide, urodilatin, which shares many of the renal actions of ANP. The mechanism underlying the diuretic action of urodilatin has not yet been examined. Accordingly, we have investigated the potential modulatory actions of both ANP and urodilatin on vasopressin-stimulated cyclic AMP (cAMP) production in microdissected inner medullary collecting duct (IMCD) segments of rat kidney. ANP and urodilatin alone (at 10−8 or 10−6 m) had no demonstrable effect on cAMP accumulation in IMCD segments. Moreover, neither ANP nor urodilatin (each at 10−6 m) significantly altered either the profile or the absolute magnitude of the cAMP response stimulated by vasopressin. These findings indicate that neither ANP nor urodilatin interacts with the vasopressin-sensitive adenylate cyclase site in the rat IMCD to contribute to its diuretic actions.

NBCn1 is a basolateral \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(\mathrm{Na}^{+}\mathrm{-HCO}_{3}^{-}\) \end{document} cotransporter in rat kidney inner medullary collecting ducts

2004 ◽  
Vol 286 (5) ◽  
pp. F903-F912 ◽  
Author(s):  
Jeppe Praetorius ◽  
Young-Hee Kim ◽  
Elena V. Bouzinova ◽  
Sebastian Frische ◽  
Aleksandra Rojek ◽  
...  
Keyword(s):  
Collecting Duct ◽  
Rat Kidney ◽  
Basolateral Membrane ◽  
Primary Cultures ◽  
Thick Ascending Limb ◽  
Medullary Thick Ascending Limb ◽  
Collecting Ducts ◽  
Basolateral Plasma Membrane ◽  
Medullary Collecting Duct ◽  
Plasma Membrane Domain

Primary cultures of rat inner medullary collecting duct (IMCD) cells Na+ dependently import [Formula: see text] across the basolateral membrane through an undefined transport protein. We used RT-PCR, immunoblotting, and immunohistochemistry to identify candidate proteins for this basolateral [Formula: see text] cotransport. The mRNA encoding the electroneutral [Formula: see text] cotransporter NBCn1 was detected as the only [Formula: see text] cotransporter in the rat inner medulla (IM) among the five characterized Na+-dependent [Formula: see text] transporters. The mRNA of a yet uncharacterized transporter-like protein, BTR1, was also present in the IM, but its expression in microdissected tubules seemed restricted to the thin limbs of Henle's loop. Immunoblotting confirmed the presence of NBCn1 as an ∼180-kDa protein of the rat IM. Anti-NBCn1 immunolabeling was confined to the basolateral plasma membrane domain of IMCD cells in the papillary two-thirds of the IM. Consistent with the presence of NBCn1, IMCD cells possessed stilbene-insensitive, Na+- and [Formula: see text]-dependent pH recovery after acidification, as assessed by fluorescence microscopy using a pH-sensitive intracellular dye. In furosemide-induced alkalotic rats, NBCn1 protein abundance was decreased in both the IM and inner stripe of outer medulla (ISOM) as determined by immunoblotting and immunohistochemistry. In contrast, NBCn1 abundance in the IM and ISOM was unchanged in NaHCO3-loaded animals, and the NBCn1 abundance increased only in the ISOM after NH4Cl loading. In conclusion, NBCn1 is a basolateral [Formula: see text] cotransporter of IMCD cells and is differentially regulated in IMCD and medullary thick ascending limb.

Effects of hypertonicity on ADH-stimulated water permeability in rat inner medullary collecting duct

1990 ◽  
Vol 258 (2) ◽  
pp. F266-F272 ◽  
Author(s):  
S. P. Nadler
Keyword(s):  
Antidiuretic Hormone ◽  
Water Permeability ◽  
Collecting Duct ◽  
Rat Kidney ◽  
Water Reabsorption ◽  
Cyclic Monophosphate ◽  
Collecting Ducts ◽  
Significant Augmentation ◽  
Medullary Collecting Duct ◽  
A Site

To assess the effects of increased tonicity on water reabsorption (Jv) in inner medullary collecting ducts (IMCD), antidiuretic hormone (ADH)-stimulated Jv and water permeability (PF) were determined in microperfused IMCD dissected from the inner medulla of rat kidney. In IMCD exposed to a 150-mosmol/kgH2O gradient in isotonic bath, ADH-stimulated PF averaged 719 +/- 93 microns/s. Symmetric addition of 75 mM NaCl to perfusate and bath resulted in a significant augmentation of ADH-stimulated PF (56%) that was reversible when initial solutions were restored. Despite the increase in PF, JV did not change but would have decreased by 16% (P less than 0.01) had PF not increased, because of the greater absolute axial increase in luminal tonicity that occurs with more hypertonic luminal solutions. When 150 mM mannitol was used to increase tonicity, similar effects were observed. However, 150 mM urea had no effect on ADH-stimulated PF. In IMCD exposed to 8-para-(chlorophenylthio)-adenosine 3',5'-cyclic monophosphate, addition of 75 mM NaCl to both and perfusate also resulted in a 76% increase in PF. These results are the first to demonstrate directly that increased effective tonicity augments ADH-stimulated PF in rat IMCD at a site distal to adenosine 3',5'-cyclic monophosphate generation. This effect may contribute to maintenance of medullary interstitial tonicity during antidiuresis by ensuring that most water reabsorption occurs more proximally within the IMCD.

Permeabilities of rat collecting duct segments to NH3 and NH4+

1991 ◽  
Vol 260 (2) ◽  
pp. F264-F272 ◽  
Author(s):  
M. F. Flessner ◽  
S. M. Wall ◽  
M. A. Knepper
Keyword(s):  
Collecting Duct ◽  
Rat Kidney ◽  
Cortical Collecting Duct ◽  
Concentration Gradients ◽  
Apparent Permeability ◽  
Collecting Ducts ◽  
Total Ammonia ◽  
Medullary Collecting Duct ◽  
Set Up

We have measured NH3 and NH4+ permeability coefficients in collecting ducts from the cortex, outer medulla, and inner medulla of the rat kidney. Isolated collecting duct segments of the rat were perfused with bicarbonate-buffered solutions containing carbonic anhydrase to eliminate any pH disequilibrium in the tubule lumen. NH3 or NH4+ concentration gradients were set up between the bath and the lumen. By measuring the total CO2 and total ammonia concentrations in the bath, the perfusate, and collected fluid, the NH3 and NH4+ concentrations were determined. Then, using the flow rate in the tubule and the tubule dimensions, we calculated the apparent permeability in each collecting duct segment for NH3 and NH4+. The NH3 permeabilities were as follows: 0.002 cm/s in the inner medullary collecting duct, 0.012 cm/s in the outer medullary collecting duct, and 0.024 cm/s in the cortical collecting duct. The NH4+ permeabilities for all segments were on the order of 10(-5) cm/s or less. The relative permeability values for the two ammonium species are consistent with the view that the secretion observed in vivo in collecting ducts is due to passive diffusion of NH3 from the interstitium to the lumen of the duct, parallel with H+ secretion.

Vasopressin induces expression of the Cl−/HCO3− exchanger SLC26A7 in kidney medullary collecting ducts of Brattleboro rats

2006 ◽  
Vol 290 (5) ◽  
pp. F1194-F1201 ◽  
Author(s):  
Snezana Petrovic ◽  
Hassane Amlal ◽  
Xuming Sun ◽  
Fiona Karet ◽  
Sharon Barone ◽  
...  
Keyword(s):  
Western Blot ◽  
Blot Analysis ◽  
Collecting Duct ◽  
Brattleboro Rats ◽  
Intercalated Cells ◽  
Collecting Ducts ◽  
Before And After ◽  
Mild Reduction ◽  
Medullary Collecting Duct

SLC26A7 is a newly identified basolateral Cl−/HCO3− exchanger specific to α-intercalated cells of the outer medullary collecting duct (OMCD). The purpose of the present experiments was to examine the expression of SLC26A7 in kidneys of vasopressin-deficient Brattleboro rats before and after treatment with desamino-Cys1,d-Arg8-vasopressin (dDAVP). Brattleboro rats were treated with dDAVP, a vasopressin analog, for 8 days, and their kidneys were examined for the expression of SLC26A7. The expression of SLC26A7 protein, as examined by immunofluorescence, was undetectable in kidneys of Brattleboro rats. However, treatment with dDAVP induced expression of SLC26A7 protein, restoring it to levels observed in normal rats. These results were verified by Western blot analysis. The mRNA expression of SLC26A7 remained unchanged in response to dDAVP. Immunofluorescent labeling demonstrated abundant levels of anion exchanger type 1 in the OMCD of Brattleboro rats and a mild reduction in response to dDAVP. The abundance of H+-ATPase was not affected by dDAVP. The increased SLC26A7 expression directly correlated with enhanced aquaporin-2 expression, which is proportional to increased interstitial osmolarity in the medulla. In conclusion, vasopressin increases the expression of SLC26A7 protein through posttranscriptional mechanisms in the OMCD. The induction of SLC26A7 by vasopressin in OMCD cells of Brattleboro rats is likely an attempt by cells to regulate their cell volume and maintain HCO3− absorption in a state associated with increased interstitial medullary tonicity.

Segmental localization of urea transporter mRNAs in rat kidney

1997 ◽  
Vol 272 (5) ◽  
pp. F654-F660 ◽  
Author(s):  
C. Shayakul ◽  
M. A. Knepper ◽  
C. P. Smith ◽  
S. R. DiGiovanni ◽  
M. A. Hediger
Keyword(s):  
Collecting Duct ◽  
Rat Kidney ◽  
Urea Transporter ◽  
Transporter Protein ◽  
Collecting Ducts ◽  
Medullary Collecting Duct ◽  
Polymerase Chain ◽  
Urea Recycling ◽  
Late Part

Renal epithelia express at least two distinct urea transporter mRNAs, termed UT1 and UT2, that are derived from a single UT gene by alternative splicing. Previous immunolocalization studies using a polyclonal antibody that does not distinguish between the protein products of these two transcripts revealed that expression of urea transporter protein is restricted to inner medullary collecting ducts and descending thin limbs of Henle's loop. To identify which transcripts account for protein expression in these two structures, we carried out reverse transcription-polymerase chain reaction studies in microdissected structures using UT1- and UT2-specific primers. UT1 mRNA was detected only in the inner medullary collecting duct, consistent with its identification as the vasopressin-regulated urea transporter. In contrast, UT2-mRNA was detected in the late part of descending thin limbs of short loops of Henle and in the inner medullary part of descending thin limbs of long loops of Henle. This localization is consistent with the predicted role of UT2 in medullary urea recycling. Thus, in conjunction with foregoing physiological studies, our data indicate that these transporters play central roles in the urinary concentrating mechanism.

Selective recognition of inositol phosphates by subtypes of the inositol trisphosphate receptor

2001 ◽  
Vol 355 (1) ◽  
pp. 59-69 ◽  
Author(s):  
Edmund P. NEROU ◽  
Andrew M. RILEY ◽  
Barry V. L. POTTER ◽  
Colin W. TAYLOR
Keyword(s):  
Hydroxy Group ◽  
Inositol Phosphates ◽  
Inositol Trisphosphate ◽  
Receptor Subtypes ◽  
Ip3 Receptors ◽  
Ip3 Receptor ◽  
Subtype Selectivity ◽  
Type 3

Synthetic analogues of inositol trisphosphate (IP3), all of which included structures equivalent to the 4,5-bisphosphate of (1,4,5)IP3, were used to probe the recognition properties of rat full-length type 1, 2 and 3 IP3 receptors expressed in insect Spodoptera frugiperda 9 cells. Using equilibrium competition binding with [3H](1,4,5)IP3 in Ca2+-free cytosol-like medium, the relative affinities of the receptor subtypes for (1,4,5)IP3 were type 3 (Kd = 11±2nM)>type 2 (Kd = 17±2nM) > type 1 (Kd = 24±4nM). (1,4,5)IP3 binding was reversibly stimulated by increased pH, but the subtypes differed in their sensitivity to pH (type 1 > type 2>type 3). For all three subtypes, the equatorial 6-hydroxy group of (1,4,5)IP3 was essential for high-affinity binding, the equatorial 3-hydroxy group significantly improved affinity, and the axial 2-hydroxy group was insignificant; a 1-phosphate (or in its absence, a 2-phosphate) improved binding affinity. The subtypes differed in the extents to which they tolerated inversion of the 3-hydroxy group of (1,4,5)IP3 (type 1>type 2>type 3), and this probably accounts for the selectivity of (1,4,6)IP3 for type 1 receptors. They also differed in their tolerance of inversion, removal or substitution (by phosphate) of the 2-hydroxy group (types 2 and 3>type 1), hence the selectivity of (1,2,4,5)IP4 for type 2 and 3 receptors. Removal of the 3-hydroxy group or its replacement by fluorine or CH2OH was best tolerated by type 3 receptors, and accounts for the selectivity of 3-deoxy(1,4,5)IP3 for type 3 receptors. Our results provide the first systematic analysis of the recognition properties of IP3 receptor subtypes and have identified the 2- and 3-positions of (1,4,5)IP3 as key determinants of subtype selectivity.

In vivo microperfusion of inner medullary collecting duct in rats: effect of amiloride and ANF

1990 ◽  
Vol 259 (2) ◽  
pp. F222-F226 ◽  
Author(s):  
H. Sonnenberg ◽  
U. Honrath ◽  
D. R. Wilson
Keyword(s):  
Collecting Duct ◽  
Rat Kidney ◽  
Inner Medullary Collecting Duct ◽  
Luminal Side ◽  
Collecting Ducts ◽  
Urinary Sample ◽  
Medullary Collecting Duct ◽  
Sites Of Action

A method is described that allows perfusion of the inner medullary collecting duct (IMCD) of the rat kidney in situ and in vivo. Fine polyethylene catheters connected to a microperfusion pump were inserted into collecting ducts via the openings at the exposed papilla tip. Perfusate contained 22Na as well as [3H]inulin. During perfusion at 30 nl/min, urine was simultaneously collected. A decrease in the Na-to-inulin concentration ratio in the urinary sample, compared with the perfusate, was taken as indicating unidirectional efflux of Na from the perfused duct system. The effects of luminal amiloride (2 X 10(-4) M) or atrial natriuretic factor (ANF, 10(-8) M) were studied. Compared with control perfusions, both agonists reduced Na efflux from the IMCD to approximately 50%, indicating luminal sites of action. Combination of amiloride and ANF at their respective concentrations had no further effect. The lack of statistically significant additivity suggests, but does not prove, that ANF, administered from the luminal side, is able to block amiloride-sensitive Na channels in the apical membrane of IMCD cells.

SNAP-23 in rat kidney: colocalization with aquaporin-2 in collecting duct vesicles

1998 ◽  
Vol 275 (5) ◽  
pp. F752-F760 ◽  
Author(s):  
Takeaki Inoue ◽  
Søren Nielsen ◽  
Beatrice Mandon ◽  
James Terris ◽  
Bellamkonda K. Kishore ◽  
...  
Keyword(s):  
Plasma Membranes ◽  
Collecting Duct ◽  
Rat Kidney ◽  
Thick Ascending Limb ◽  
Principal Cells ◽  
Aquaporin 2 ◽  
Collecting Ducts ◽  
Medullary Collecting Duct ◽  
Intracellular Vesicles ◽  
Regulated Trafficking

Vesicle targeting proteins (“SNAREs”) have been proposed to direct vasopressin-induced trafficking of aquaporin-2 water channels in kidney collecting ducts. A newly identified SNARE protein, SNAP-23, is proposed to mediate vesicle targeting to the plasma membrane in diverse tissues. The current studies were done to determine whether SNAP-23 is expressed in collecting ducts with an intracellular distribution compatible with a role in aquaporin-2 trafficking. RT-PCR demonstrated SNAP-23 mRNA in microdissected collecting ducts and other tubular segments including the proximal tubule and thick ascending limb. Immunoblotting using a polyclonal antibody raised against a COOH-terminal peptide revealed a solitary band at an apparent molecular mass of 30 kDa in renal medullary membrane fractions and inner medullary collecting duct suspensions. Differential centrifugation revealed that SNAP-23 is present in membrane fractions including the low-density fraction enriched in intracellular vesicles. Immunocytochemistry revealed SNAP-23 labeling at both the apex and the cytoplasm of collecting duct principal cells. Immunoblotting of intracellular vesicles immunoisolated using an aquaporin-2 antibody revealed the presence of both SNAP-23 and synaptobrevin-2 (VAMP-2) in aquaporin-2-bearing vesicles. We conclude that SNAP-23 is strongly expressed in collecting duct principal cells, consistent with a role in vasopressin-regulated trafficking of aquaporin-2. However, localization of SNAP-23 in both intracytoplasmic vesicles and plasma membranes suggests a function different from that originally proposed for SNAP-25 in synaptic vesicle targeting.

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