Autocrine role of endothelin in rat IMCD: inhibition of AVP-induced cAMP accumulation

1993 ◽  
Vol 265 (1) ◽  
pp. F126-F129 ◽  
Author(s):  
D. E. Kohan ◽  
A. K. Hughes
Keyword(s):  
Arginine Vasopressin ◽  
Collecting Duct ◽  
Camp Accumulation ◽  
Semipermeable Membranes ◽  
Endothelin 1 ◽  
Cyclic Monophosphate ◽  
Nephron Segment ◽  
Specific Receptors ◽  
Medullary Collecting Duct

Exogenous endothelin-1 (ET-1) inhibits arginine vasopressin (AVP)-induced adenosine 3',5'-cyclic monophosphate (cAMP) accumulation in the inner medullary collecting duct (IMCD). Since ET-1 is produced by, and binds to specific receptors on, the IMCD, the possibility exists that ET-1 is an autocrine regulator of AVP action in this nephron segment. To test this hypothesis, rat IMCD cells grown on semipermeable membranes were exposed to rabbit anti-ET antisera or nonimmune rabbit sera (NRS). AVP (10(-9)M) caused a significantly greater accumulation of cAMP in confluent IMCD monolayers preincubated in ET-1 antisera compared with NRS. ET-1 (10(-8) M) inhibited the AVP-induced rise in cAMP by 65% in cells preincubated in ET-1 antisera, but had no effect in NRS-treated cells. Finally, 125I-ET-1 (30 pM) binding was increased sixfold in IMCD preincubated in anti-ET-1 antisera. These data indicate that ET causes tonic autocrine inhibition of AVP responsiveness in the IMCD.

Endothelin-1 stimulates NO production and inhibits cAMP accumulation in rat inner medullary collecting duct through independent pathways

2006 ◽  
Vol 290 (6) ◽  
pp. F1315-F1319 ◽  
Author(s):  
Peter K. Stricklett ◽  
Alisa K. Hughes ◽  
Donald E. Kohan
Keyword(s):  
Collecting Duct ◽  
Cell Suspensions ◽  
No Production ◽  
Camp Accumulation ◽  
No Donors ◽  
Endothelin 1 ◽  
Inner Medullary Collecting Duct ◽  
Nos Inhibitors ◽  
Medullary Collecting Duct ◽  
Spermine Nonoate

Endothelin-1 (ET-1) inhibition of vasopressin (AVP)-stimulated cAMP accumulation in the collecting duct has been hypothesized to be mediated, at least in part, by nitric oxide (NO). To examine this, the effect of ET-1 on NO production by acutely isolated rat inner medullary collecting duct (IMCD) cell suspensions and the role of NO in mediating ET-1 effects on AVP-stimulated cAMP accumulation were studied. ET-1 dose dependently (first evident at 100 pM ET-1) increased IMCD NO production as determined by DAF-FM fluorescence. ETB receptor (BQ-788), but not ETA receptor (BQ-123), antagonism blocked this effect. Nonspecific NO synthase (NOS) inhibitors [ NG-nitro-l-arginine methyl ester (l-NAME) or NG-monomethyl-l-arginine] or NOS-1 inhibitors (SMTC or VNIO) inhibited the ET-1 response, whereas NOS-2 or NOS-3 inhibitors (l-NAA or 1400W) were ineffective. ET-1 also increased cGMP accumulation. ET-1 caused a 35% reduction in AVP-stimulated cAMP levels; however, this response was not affected by l-NAME or SMTC. The addition of l-arginine, NADPH, tetrahydrobiopterin, or tempol (to reduce superoxide-dependent conversion of NO to peroxynitrate) did not affect the response. NO donors (SNAP or spermine NONOate), at concentrations that stimulated DAF-FM fluorescence and increased cGMP levels, did not alter AVP-stimulated cAMP accumulation in the IMCD cell suspensions. In conclusion, ET-1 stimulates IMCD NO production through activation of the ETB receptor and NOS-1. However, neither ET-1-mediated NO production nor NO donors inhibit AVP-stimulated cAMP accumulation, indicating that NO does not mediate ET-1 inhibition of cAMP production by the IMCD.

Endothelin-1 is an autocrine factor in rat inner medullary collecting ducts

1992 ◽  
Vol 263 (4) ◽  
pp. F607-F612 ◽  
Author(s):  
D. E. Kohan ◽  
E. Padilla
Keyword(s):  
Collecting Duct ◽  
Receptor Activation ◽  
Endothelin Receptors ◽  
Semipermeable Membranes ◽  
Endothelin 1 ◽  
Autocrine Regulation ◽  
Basolateral Side ◽  
Collecting Ducts ◽  
Medullary Collecting Duct ◽  
Autocrine Factor

Endothelin-1 (ET-1) may be an important factor in the regulation of inner medullary collecting duct (IMCD) physiology. This segment of the nephron synthesizes ET-1, expresses endothelin receptors, and responds to exogenous ET-1 by reducing Na(+)-K(+)-ATPase activity and water transport. Taken together, these findings suggest an autocrine role for ET-1 in the regulation of IMCD function; however, because of the polarized nature of the IMCD, it is not known if ET-1 secretion, receptors, and receptor activation occur on the same side of the cell. To examine this question, rat IMCD cells were grown to confluence on semipermeable membranes. These cells exhibited polar morphology with high transepithelial electrical resistances. Immunoreactive ET-1 was secreted primarily into the basolateral side. Furthermore, 125I-ET-1 bound predominantly to the basolateral surface. Finally, ET-1 (10(-8) M) stimulated prostaglandin E2 production only when added to the basolateral side. These data indicate, therefore, that ET-1 is capable of autocrine regulation of IMCD cells and that this effect occurs predominantly on the basolateral side.

cGMP mediates effects of atrial peptides on medullary collecting duct cells

1987 ◽  
Vol 252 (3) ◽  
pp. F551-F559 ◽  
Author(s):  
M. L. Zeidel ◽  
P. Silva ◽  
B. M. Brenner ◽  
J. L. Seifter
Keyword(s):  
Collecting Duct ◽  
Renal Medulla ◽  
Fold Increase ◽  
Inhibitory Effect ◽  
Cyclic Monophosphate ◽  
Transport Effects ◽  
Collecting Duct Cells ◽  
Medullary Collecting Duct ◽  
Camp Levels

Atrial natriuretic peptides (ANP) stimulate renal Na+ excretion by poorly understood mechanisms, possibly involving direct inhibition of Na+ transport in the renal medulla. We have previously shown that human ANP 4-28 (hANP) inhibits Na+ entry-dependent O2 consumption (QO2) in rabbit inner medullary collecting duct (IMCD) cells. Because ANP actions in other tissues appear to be mediated by guanosine 3',5'-cyclic monophosphate (cGMP), the present studies examined the role of cyclic nucleotides in IMCD cell responses to ANP. 8-Bromo-cGMP (8-BrcGMP) diminished QO2 by 23.5 +/- 1.2% (SE) in IMCD cells but had no effect in cells derived from outer medullary collecting duct (OMCD); dibutyryl-adenosine 3',5'-cyclic monophosphate (cAMP) was without effect in IMCD cells. The inhibitory effect of BrcGMP was not additive with ANP, amiloride, or ouabain. Amphotericin, which enhances Na+ entry into cells, prevented the inhibitory effect of 8-BrcGMP. These results indicate that 8-BrcGMP, like ANP, inhibited Na+ entry in IMCD cells. hANP stimulated a 10-fold increase in cGMP in IMCD cells without altering IMCD cAMP levels or OMCD cGMP levels. Isobutyl methylxanthine, which inhibits phosphodiesterase activity, enhanced both cGMP accumulation and inhibition of QO2 by submaximal levels (10(-9) M) of ANP. Nitroprusside raised cGMP levels in both IMCD and OMCD cells but inhibited QO2 only in IMCD cells. We conclude that cGMP mediates the transport effects of ANP in IMCD cells. Our results indicate that cGMP may play an important role in the regulation of sodium transport in renal epithelia.

scholarly journals Role of the medullary collecting duct in potassium excretion in potassium-adapted animals

1981 ◽  
Vol 20 (5) ◽  
pp. 655-662 ◽  
Author(s):  
Donald A. Schon ◽  
Karen A. Backman ◽  
John P. Hayslett
Keyword(s):  
Collecting Duct ◽  
Potassium Excretion ◽  
Medullary Collecting Duct

scholarly journals Potential role of purinergic signaling in urinary concentration in inner medulla: insights from P2Y2 receptor gene knockout mice

2008 ◽  
Vol 295 (6) ◽  
pp. F1715-F1724 ◽  
Author(s):  
Yue Zhang ◽  
Jeff M. Sands ◽  
Donald E. Kohan ◽  
Raoul D. Nelson ◽  
Christopher F. Martin ◽  
...  
Keyword(s):  
Gene Knockout ◽  
Purinergic Signaling ◽  
Collecting Duct ◽  
Receptor Gene ◽  
Urinary Concentration ◽  
P2y2 Receptor ◽  
Concentration Gradients ◽  
Gene Knockout Mice ◽  
Medullary Collecting Duct

Osmotic reabsorption of water through aquaporin-2 (AQP2) in the inner medulla is largely dependent on the urea concentration gradients generated by urea transporter (UT) isoforms. Vasopressin (AVP) increases expression of both AQP2 and UT-A isoforms. Activation of the P2Y2 receptor (P2Y2-R) in the medullary collecting duct inhibits AVP-induced water flow. To gain further insights into the overarching effect of purinergic signaling on urinary concentration, we compared the protein abundances of AQP2 and UT-A isoforms between P2Y2-R knockout (KO) and wild-type (WT) mice under basal conditions and following AVP administration. Under basal conditions (a gel diet for 10 days), KO mice concentrated urine to a significantly higher degree, with 1.8-, 1.66-, and 1.29-fold higher protein abundances of AQP2, UT-A1, and UT-A2, respectively, compared with WT, despite comparable circulating AVP levels in both groups. Infusion of 1-desamino-8-d-arginine vasopressin (dDAVP; desmopressin; 1 ng/h sc) for 5 days resulted in 2.14-, 2.6-, and 2.22-fold higher protein abundances of AQP2, AQP3, and UT-A1, respectively, in the inner medullas of KO mice compared with WT mice. In response to acute (45 min) stimulation by AVP (0.2 unit/mouse sc), UT-A1 protein increased by 1.39- and 1.54-fold in WT and KO mice, respectively. These data suggest that genetic deletion of P2Y2-R results in increased abundances of key proteins involved in urinary concentration in the inner medulla, both under basal conditions and following AVP administration. Thus purinergic regulation may play a potential overarching role in balancing the effect of AVP on the urinary concentration mechanism.

Role of SNAP-23 in trafficking of H+-ATPase in cultured inner medullary collecting duct cells

2001 ◽  
Vol 280 (4) ◽  
pp. C775-C781 ◽  
Author(s):  
Abhijit Banerjee ◽  
Guangmu Li ◽  
Edward A. Alexander ◽  
John H. Schwartz
Keyword(s):  
Botulinum Toxin ◽  
Apical Membrane ◽  
Collecting Duct ◽  
Snare Complex ◽  
Attachment Protein ◽  
Regulated Exocytosis ◽  
Inner Medullary Collecting Duct ◽  
Sensitive Factor ◽  
Medullary Collecting Duct

The trafficking of H+-ATPase vesicles to the apical membrane of inner medullary collecting duct (IMCD) cells utilizes a mechanism similar to that described in neurosecretory cells involving soluble N-ethylmaleimide-sensitive factor attachment protein target receptor (SNARE) proteins. Regulated exocytosis of these vesicles is associated with the formation of SNARE complexes. Clostridial neurotoxins that specifically cleave the target (t-) SNARE, syntaxin-1, or the vesicle SNARE, vesicle-associated membrane protein-2, reduce SNARE complex formation, H+-ATPase translocation to the apical membrane, and inhibit H+ secretion. The purpose of these experiments was to characterize the physiological role of a second t-SNARE, soluble N-ethylmaleimide-sensitive factor attachment protein (SNAP)-23, a homologue of the neuronal SNAP-25, in regulated exocytosis of H+-ATPase vesicles. Our experiments document that 25–50 nM botulinum toxin (Bot) A or E cleaves rat SNAP-23 and thereby reduces immunodetectable and35S-labeled SNAP-23 by >60% within 60 min. Addition of 25 nM BotE to IMCD homogenates reduces the amount of the 20 S-like SNARE complex that can be immunoprecipitated from the homogenate. Treatment of intact IMCD monolayers with BotE reduces the amount of H+-ATPase translocated to the apical membrane by 52 ± 2% of control and reduces the rate of H+ secretion by 77 ± 3% after acute cell acidification. We conclude that SNAP-23 is a substrate for botulinum toxin proteolysis and has a critical role in the regulation of H+-ATPase exocytosis and H+ secretion in these renal epithelial cells.

Differential effect of basolateral and apical adenosine on AVP-stimulated cAMP formation in primary culture of IMCD

1992 ◽  
Vol 263 (2) ◽  
pp. F268-F276 ◽  
Author(s):  
Y. Yagil
Keyword(s):  
Arginine Vasopressin ◽  
Collecting Duct ◽  
Inhibitory Effect ◽  
Detectable Effect ◽  
Inhibitory Effects ◽  
Tubule Cell ◽  
Adenosine Antagonist ◽  
A1 Receptor ◽  
Medullary Collecting Duct ◽  
Camp Formation

It has been recently established that adenosine interferes with the ability of arginine vasopressin (AVP) to generate adenosine 3',5'-cyclic monophosphate (cAMP) in inner medullary collecting duct (IMCD) cells in culture. The aim of the current study was to determine whether this interaction of adenosine with AVP is mediated by adenosine from the basolateral (B) and/or the apical (A) surface of the tubule cell. Cells from rat IMCD were grown to confluence in monolayers on porous filters. Adenosine (5 x 10(-8)-10(-4) M) applied to the B or A surface of the cell had no detectable effect on basal cAMP formation. AVP, 10(-9)-10(-6) M, increased cAMP formation from both B and A surfaces of the cell. When AVP was applied to the B surface, 10(-6) M adenosine inhibited AVP-stimulated cAMP formation from the B side only, whereas adenosine at 10(-4) M inhibited cAMP formation from both B and A sides. The inhibitory effect of adenosine was reproduced with N6-cyclohexyladenosine (CHA) from both B and A surfaces. 5'-(N-ethylcarboxamido)adenosine (NECA) and 2',5'-dideoxyadenosine (DDA) inhibited cAMP formation from the B surface only. When AVP wasapplied to the A surface, the inhibitory effects of adenosine were the same as when AVP was applied to the B surface; CHA, NECA, and DDA inhibited AVP-stimulated cAMP formation from both the B and A surfaces. 1,3-Dipropyl-8-cyclopentylxanthine (DPCPX), an adenosine antagonist with selectivity for the A1 receptor, prevented the inhibitory effects of adenosine, CHA, and NECA on AVP-stimulated cAMP formation.(ABSTRACT TRUNCATED AT 250 WORDS)

Response of rat inner medullary collecting duct to epidermal growth factor

1989 ◽  
Vol 256 (6) ◽  
pp. F1117-F1124 ◽  
Author(s):  
R. C. Harris
Keyword(s):  
Growth Factor ◽  
Binding Sites ◽  
Collecting Duct ◽  
Affinity Binding ◽  
Inner Medullary Collecting Duct ◽  
Duct Cells ◽  
Epidermal Growth ◽  
Collecting Duct Cells ◽  
Medullary Collecting Duct

Urine is an abundant source of epidermal growth factor (EGF) and prepro-EGF has been localized to the thick ascending limb and distal convoluted tubule of the kidney. However, the functional role of EGF in the kidney is poorly understood. Determination of EGF receptors and functional responses to EGF in intrarenal structures distal to the site of renal EGF production may prove critical to our understanding of the role of this peptide. These studies were designed to investigate the response to EGF of rat inner medullary collecting duct cells in culture and in freshly isolated suspensions. Primary cultures of inner medullary collecting duct cells demonstrated equilibrium binding of 125I-labeled EGF at 4 and 23 degrees C. At 23 degrees C, there was 89 +/- 1% specific binding (n = 30). Scatchard analysis of 125I-EGF binding suggested the presence of both high-affinity binding with a dissociation constant (Kd) of 5 X 10(-10) M and maximal binding sites (Ro) of 2.7 X 10(3) binding sites/cell and low-affinity binding, with Kd of 8.3 X 10(-9) M and Ro of 1.8 X 10(4) binding sites/cell. Bound EGF, 68 +/- 3%, was internalized by 45 min. EGF binding was not inhibited by antidiuretic hormone, atrial natriuretic peptide or bradykinin at 23 degrees C, but there was concentration-dependent inhibition of binding by transforming growth factor-alpha. Incubation with phorbol myristate acetate decreased 125I-EGF binding in a concentration-dependent manner. 125I-EGF binding was also demonstrated in freshly isolated suspensions of rat inner medullary collecting duct cells.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Role of PKC and AMPK in hypertonicity-stimulated water reabsorption in rat inner medullary collecting ducts

2019 ◽  
Vol 316 (2) ◽  
pp. F253-F262 ◽  
Author(s):  
Josephine K. Liwang ◽  
Joseph A. Ruiz ◽  
Lauren M. LaRocque ◽  
Fitra Rianto ◽  
Fuying Ma ◽  
...  
Keyword(s):  
Water Permeability ◽  
Collecting Duct ◽  
Adenosine Monophosphate ◽  
Osmotic Water Permeability ◽  
Water Reabsorption ◽  
Compound C ◽  
Ampk Phosphorylation ◽  
Osmotic Water ◽  
Medullary Collecting Duct

Hypertonicity increases water permeability, independently of vasopressin, in the inner medullary collecting duct (IMCD) by increasing aquaporin-2 (AQP2) membrane accumulation. We investigated whether protein kinase C (PKC) and adenosine monophosphate kinase (AMPK) are involved in hypertonicity-regulated water permeability. Increasing perfusate osmolality from 150 to 290 mosmol/kgH2O and bath osmolality from 290 to 430 mosmol/kgH2O significantly stimulated osmotic water permeability. The PKC inhibitors chelerythrine (10 µM) and rottlerin (50 µM) significantly reversed the increase in osmotic water permeability stimulated by hypertonicity in perfused rat terminal IMCDs. Chelerythrine significantly increased phosphorylation of AQP2 at S261 but not at S256. Previous studies show that AMPK is stimulated by osmotic stress. We tested AMPK phosphorylation under hypertonic conditions. Hypertonicity significantly increased AMPK phosphorylation in inner medullary tissues. Blockade of AMPK with Compound C decreased hypertonicity-stimulated water permeability but did not alter phosphorylation of AQP2 at S256 and S261. AICAR, an AMPK stimulator, caused a transient increase in osmotic water permeability and increased phosphorylation of AQP2 at S256. When inner medullary tissue was treated with the PKC activator phorbol dibutyrate (PDBu), the AMPK activator metformin, or both, AQP2 phosphorylation at S261 was decreased with PDBu or metformin alone, but there was no additive effect on phosphorylation with PDBu and metformin together. In conclusion, hypertonicity regulates water reabsorption by activating PKC. Hypertonicity-stimulated water reabsorption by PKC may be related to the decrease in endocytosis of AQP2. AMPK activation promotes water reabsorption, but the mechanism remains to be determined. PKC and AMPK do not appear to act synergistically to regulate water reabsorption.

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