Endothelin and nitric oxide mediate adaptation of the cortical collecting duct to metabolic acidosis

2006 ◽  
Vol 291 (4) ◽  
pp. F866-F873 ◽  
Author(s):  
Shuichi Tsuruoka ◽  
Seiji Watanabe ◽  
Jeffrey M. Purkerson ◽  
Akio Fujimura ◽  
George J. Schwartz
Keyword(s):  
Nitric Oxide ◽  
Metabolic Acidosis ◽  
Receptor Antagonist ◽  
Guanylate Cyclase ◽  
Kinase Inhibitor ◽  
Collecting Duct ◽  
Bicarbonate Transport ◽  
Receptor Subtypes ◽  
Cortical Collecting Duct

Endothelin (ET) and nitric oxide (NO) modulate ion transport in the kidney. In this study, we defined the function of ET receptor subtypes and the NO guanylate cyclase signaling pathway in mediating the adaptation of the rabbit cortical collecting duct (CCD) to metabolic acidosis. CCDs were perfused in vitro and incubated for 3 h at pH 6.8, and bicarbonate transport or cell pH was measured before and after acid incubation. Luminal chloride was reversibly removed to isolate H+ and HCO3− secretory fluxes and to raise the pH of β-intercalated cells. Acid incubation caused reversal of polarity of net HCO3− transport from secretion to absorption, comprised of a 40% increase in H+ secretion and a 75% decrease in HCO3− secretion. The ETB receptor antagonist BQ-788, as well as the NO synthase inhibitor, NG-nitro-l-arginine methyl ester (l-NAME), attenuated the adaptive decrease in HCO3− secretion by 40%, but only BQ-788 inhibited the adaptive increase in H+ secretion. There was no effect of inactive d-NAME or the ETA receptor antagonist BQ-123. Both BQ-788 and l-NAME inhibited the acid-induced inactivation (endocytosis) of the apical Cl−/HCO3− exchanger. The guanylate cyclase inhibitor LY-83583 and cGMP-dependent protein kinase inhibitor KT-5823 affected HCO3− transport similarly to l-NAME. These data indicate that signaling via the ETB receptor regulates the adaptation of the CCD to metabolic acidosis and that the NO guanylate cyclase component of ETB receptor signaling mediates downregulation of Cl−/HCO3− exchange and HCO3− secretion.

scholarly journals Effects of ammonia on bicarbonate transport in the cortical collecting duct

2000 ◽  
Vol 278 (2) ◽  
pp. F219-F226 ◽  
Author(s):  
Amy E. Frank ◽  
Charles S. Wingo ◽  
I. David Weiner
Keyword(s):  
Collecting Duct ◽  
Potassium Transport ◽  
Bicarbonate Transport ◽  
Cortical Collecting Duct ◽  
Intracellular Acidification ◽  
Bicarbonate Reabsorption ◽  
Atpase Inhibitors ◽  
Collecting Ducts ◽  
Stimulation Of

Both acidosis and hypokalemia stimulate renal ammoniagenesis, and both regulate urinary proton and potassium excretion. We hypothesized that ammonia might play an important role in this processing by stimulating H+-K+-ATPase-mediated ion transport. Rabbit cortical collecting ducts (CCD) were studied using in vitro microperfusion, bicarbonate reabsorption was measured using microcalorimetry, and intracellular pH (pHi) was measured using the fluorescent, pH-sensitive dye, 2′,7′-bis(2-carboxyethyl)-5(6)-carboxyfluorescein (BCECF). Ammonia caused a concentration-dependent increase in net bicarbonate reabsorption that was inhibited by luminal addition of either of the H+-K+-ATPase inhibitors, Sch-28080 or ouabain. The stimulation of net bicarbonate reabsorption was not mediated through apical H+-ATPase, basolateral Na+-K+-ATPase, or luminal electronegativity. Although ammonia caused intracellular acidification, similar changes in pHi induced by inhibiting basolateral Na+/H+ exchange did not alter net bicarbonate reabsorption. We conclude that ammonia regulates CCD proton and potassium transport, at least in part, by stimulating apical H+-K+-ATPase.

Effects of luminal flow and nucleotides on [Ca2+]i in rabbit cortical collecting duct

2002 ◽  
Vol 283 (3) ◽  
pp. F437-F446 ◽  
Author(s):  
Craig B. Woda ◽  
Maurilo Leite ◽  
Rajeev Rohatgi ◽  
Lisa M. Satlin
Keyword(s):  
Flow Rate ◽  
Purinergic Receptor ◽  
Collecting Duct ◽  
Basolateral Membrane ◽  
Cell Types ◽  
P2 Receptors ◽  
Receptor Subtypes ◽  
Cortical Collecting Duct ◽  
Luminal Perfusion

Nucleotide binding to purinergic P2 receptors contributes to the regulation of a variety of physiological functions in renal epithelial cells. Whereas P2 receptors have been functionally identified at the basolateral membrane of the cortical collecting duct (CCD), a final regulatory site of urinary Na+, K+, and acid-base excretion, controversy exists as to whether apical purinoceptors exist in this segment. Nor has the distribution of receptor subtypes present on the unique cell populations that constitute Ca2+ the CCD been established. To examine this, we measured nucleotide-induced changes in intracellular Ca2+ concentration ([Ca2+]i) in fura 2-loaded rabbit CCDs microperfused in vitro. Resting [Ca2+]i did not differ between principal and intercalated cells, averaging ∼120 nM. An acute increase in tubular fluid flow rate, associated with a 20% increase in tubular diameter, led to increases in [Ca2+]i in both cell types. Luminal perfusion of 100 μM UTP or ATP-γ-S, in the absence of change in flow rate, caused a rapid and transient approximately fourfold increase in [Ca2+]i in both cell types ( P< 0.05). Luminal suramin, a nonspecific P2 receptor antagonist, blocked the nucleotide- but not flow-induced [Ca2+]i transients. Luminal perfusion with a P2X (α,β-methylene-ATP), P2X7 (benzoyl-benzoyl-ATP), P2Y1 (2-methylthio-ATP), or P2Y4/P2Y6 (UDP) receptor agonist had no effect on [Ca2+]i. The nucleotide-induced [Ca2+]i transients were inhibited by the inositol-1,4,5-triphosphate receptor blocker 2-aminoethoxydiphenyl borate, thapsigargin, which depletes internal Ca2+ stores, luminal perfusion with a Ca2+-free perfusate, or the L-type Ca2+ channel blocker nifedipine. These results suggest that luminal nucleotides activate apical P2Y2 receptors in the CCD via pathways that require both internal Ca2+mobilization and extracellular Ca2+ entry. The flow-induced rise in [Ca2+]i is apparently not mediated by apical P2 purinergic receptor signaling.

Total CO2 transport in rat cortical collecting duct in chloride-depletion alkalosis

1990 ◽  
Vol 258 (4) ◽  
pp. F848-F853 ◽  
Author(s):  
J. D. Gifford ◽  
K. Sharkins ◽  
J. Work ◽  
R. G. Luke ◽  
J. H. Galla
Keyword(s):  
Peritoneal Dialysis ◽  
Metabolic Alkalosis ◽  
Collecting Duct ◽  
Bicarbonate Transport ◽  
Cortical Collecting Duct ◽  
Co2 Transport ◽  
Chloride Depletion

Previous studies in chloride-depletion metabolic alkalosis (CDA) generated by intraperitoneal dialysis have suggested major alterations in chloride and bicarbonate transport beyond the distal convoluted tubule. To investigate the possible role of the cortical collecting duct (CCD) in the pathophysiology of CDA, isolated CCD segments were perfused in vitro from either control (CON) rats dialyzed against Ringer-bicarbonate or those made alkalotic by peritoneal dialysis with 0.15 M NaHCO3. Tubules from CDA animals secreted CO2 for greater than or equal to 3 h after dissection (-22.4 +/- 7.2 pmol.mm-1.min-1) compared with CON tubules that absorbed CO2 (18.3 +/- 4.2 pmol.mm-1.min-1). Replacement of luminal chloride with gluconate in the perfusate abolished net total CO2 (tCO2) secretion in tubules from CDA animals (from -21.5 +/- 4.5 to -2.7 +/- 2.3 pmol.mm-1.min-1) but did not alter net tCO2 absorption in tubules from CON animals. In contrast, removal of bath chloride increased net tCO2 secretion (-12.1 +/- 2.9 to -26.1 +/- 3.6 pmol.mm-1.min-1) in CDA tubules, whereas net tCO2 flux was altered from absorption to secretion in CON tubules (15.5 +/- 4.0 to -13.6 +/- 9.2 pmol.mm-1.min-1). These results demonstrate that 1) CDA generated in vivo within 45 min results in stable net tCO2 secretion in vitro up to 240 min in the CCD; 2) luminal chloride is necessary for tCO2 secretion; 3) the shift of net tCO2 flux from absorption to secretion in CON tubules in vitro was not sustained in contrast to CDA tubules.(ABSTRACT TRUNCATED AT 250 WORDS)

Bicarbonate transport by isolated perfused rat collecting ducts

1985 ◽  
Vol 249 (4) ◽  
pp. F485-F489 ◽  
Author(s):  
J. L. Atkins ◽  
M. B. Burg
Keyword(s):  
Regulatory Mechanism ◽  
Collecting Duct ◽  
Bicarbonate Transport ◽  
Bicarbonate Secretion ◽  
Cortical Collecting Duct ◽  
Acid Excretion ◽  
Alkaline Urine ◽  
Acid Urine ◽  
Collecting Ducts

Previously, bicarbonate transport was measured in isolated perfused rabbit cortical collecting ducts (CCD) and outer medullary collecting ducts (OMCD). Rabbit CCD either absorbed or secreted bicarbonate in vitro, depending on whether the animals were treated with NH4Cl or NaHCO3, but the OMCD absorbed bicarbonate regardless of the treatment. The general significance of these findings (particularly the bicarbonate secretion) was questioned because rabbits are herbivores that normally excrete alkaline urine. Therefore, we have now studied rats, an omnivorous species, that normally excrete acid urine. The overall pattern of bicarbonate transport in rats was similar to that previously found in rabbits. CCD from rats given NaHCO3 initially secreted bicarbonate, but those from rats given NH4Cl absorbed bicarbonate. Rat OMCD all absorbed bicarbonate, regardless of the treatment. The significant differences between the results with rats and rabbits were 1) a marked shift in bicarbonate transport in control and bicarbonate-loaded rat (but not rabbit) CCD with time of perfusion in vitro from secretion toward absorption; this implies an additional regulatory mechanism in rats; and 2) rat OMCDs absorbing bicarbonate more than three times faster than rabbit OMCD. These results provide additional evidence that conditioned changes in cortical collecting duct bicarbonate transport, now observed in two different species, play a significant role in the control of net acid excretion.

scholarly journals Nitric oxide reduces Cl− absorption in the mouse cortical collecting duct through an ENaC-dependent mechanism

2013 ◽  
Vol 304 (11) ◽  
pp. F1390-F1397 ◽  
Author(s):  
Vladimir Pech ◽  
Monika Thumova ◽  
Sergey I. Dikalov ◽  
Edith Hummler ◽  
Bernard C. Rossier ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Angiotensin Ii ◽  
Collecting Duct ◽  
No Synthase ◽  
Apical Plasma Membrane ◽  
No Production ◽  
Cortical Collecting Duct ◽  
No Donor ◽  
Genetic Ablation

Since nitric oxide (NO) participates in the renal regulation of blood pressure, in part, by modulating transport of Na+ and Cl− in the kidney, we asked whether NO regulates net Cl− flux ( JCl) in the cortical collecting duct (CCD) and determined the transporter(s) that mediate NO-sensitive Cl− absorption. Cl− absorption was measured in CCDs perfused in vitro that were taken from aldosterone-treated mice. Administration of an NO donor (10 μM MAHMA NONOate) reduced JCl and transepithelial voltage ( VT) both in the presence or absence of angiotensin II. However, reducing endogenous NO production by inhibiting NO synthase (100 μM NG-nitro-l-arginine methyl ester) increased JCl only in the presence of angiotensin II, suggesting that angiotensin II stimulates NO synthase activity. To determine the transport process that mediates NO-sensitive changes in JCl, we examined the effect of NO on JCl following either genetic ablation or chemical inhibition of transporters in the CCD. Since the application of hydrochlorothiazide (100 μM) or bafilomycin (5 nM) to the perfusate or ablation of the gene encoding pendrin did not alter NO-sensitive JCl, NO modulates JCl independent of the Na+-dependent Cl−/HCO3− exchanger (NDCBE, Slc4a8), the A cell apical plasma membrane H+-ATPase and pendrin. In contrast, both total and NO-sensitive JCl and VT were abolished with application of an epithelial Na+ channel (ENaC) inhibitor (3 μM benzamil) to the perfusate. We conclude that NO reduces Cl− absorption in the CCD through a mechanism that is ENaC-dependent.

scholarly journals Intercalated cell-specific Rh B glycoprotein deletion diminishes renal ammonia excretion response to hypokalemia

2013 ◽  
Vol 304 (4) ◽  
pp. F422-F431 ◽  
Author(s):  
Jesse M. Bishop ◽  
Hyun-Wook Lee ◽  
Mary E. Handlogten ◽  
Ki-Hwan Han ◽  
Jill W. Verlander ◽  
...  
Keyword(s):  
Metabolic Acidosis ◽  
Collecting Duct ◽  
Ammonia Excretion ◽  
Ammonia Concentration ◽  
Intercalated Cells ◽  
Cortical Collecting Duct ◽  
Intercalated Cell ◽  
Transporter Family ◽  
Total Ammonia ◽  
Normal Increase

The ammonia transporter family member, Rh B Glycoprotein (Rhbg), is an ammonia-specific transporter heavily expressed in the kidney and is necessary for the normal increase in ammonia excretion in response to metabolic acidosis. Hypokalemia is a common clinical condition in which there is increased renal ammonia excretion despite the absence of metabolic acidosis. The purpose of this study was to examine Rhbg's role in this response through the use of mice with intercalated cell-specific Rhbg deletion (IC-Rhbg-KO). Hypokalemia induced by feeding a K+-free diet increased urinary ammonia excretion significantly. In mice with intact Rhbg expression, hypokalemia increased Rhbg protein expression in intercalated cells in the cortical collecting duct (CCD) and in the outer medullary collecting duct (OMCD). Deletion of Rhbg from intercalated cells inhibited hypokalemia-induced changes in urinary total ammonia excretion significantly and completely prevented hypokalemia-induced increases in urinary ammonia concentration, but did not alter urinary pH. We conclude that hypokalemia increases Rhbg expression in intercalated cells in the cortex and outer medulla and that intercalated cell Rhbg expression is necessary for the normal increase in renal ammonia excretion in response to hypokalemia.

scholarly journals Role of α1-adrenergic receptor subtypes in contractility of the rabbit abdominal aorta in vitro

2013 ◽  
Vol 82 (3) ◽  
pp. 331-336 ◽  
Author(s):  
Jan Gnus ◽  
Albert Czerski ◽  
Stanisław Ferenc ◽  
Wojciech Zawadzki ◽  
Wojciech Witkiewicz ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Receptor Antagonist ◽  
Abdominal Aorta ◽  
Adrenergic Receptor ◽  
Receptor Subtypes ◽  
Organ Bath ◽  
Dependent Manner ◽  
Receptor Antagonists ◽  
Selective Antagonists

Investigation of the effect of α1-adrenergic receptor subtypes on the contraction of the abdominal aorta will allow for more effective treatment of hypertension by use of selective antagonists. The aim of the study was to evaluate the participation of α1-adrenergic receptor subtypes in the contractility of the aortic smooth muscle cells in rabbits. The in vitro experiments were performed in isolated tissue preparations from 30 adult female New Zealand rabbits. The abdominal aortic sections were placed in organ bath chambers and contracted with increasing doses of non-selective α1-adrenergic receptor agonist phenylephrine without pre-incubation or after incubation in α1-adrenergic receptor subtype-selective or non-selective antagonists. Separate sections were incubated with increasing concentrations of antagonists. Phenylephrine caused maximal rise in arterial smooth muscle tone to 4.75 ± 0.47 mN. The most potent in blocking phenylephrine induced contraction was 5-metylurapidil (α1A-adrenergic receptor antagonist) followed by phentolamine and prazosin (non-selective α1-adrenergic receptor antagonists); BMY 7378 (α1D-adrenergic receptor antagonist), cyclazosin and L-765.314 (α1B-adrenergic receptor antagonists) were less effective. All antagonists, except BMY 7378 elicited relaxation of non-precontracted aorta in dose dependent manner. Our results indicate that postsynaptic α1A receptors are the most potent in producing rabbit abdominal aorta contraction, while α1B and α1D subtypes are less effective.

M1 and M3 muscarinic antagonists inhibit human nasal glandular secretion in vitro

1992 ◽  
Vol 73 (5) ◽  
pp. 2069-2073 ◽  
Author(s):  
J. Mullol ◽  
J. N. Baraniuk ◽  
C. Logun ◽  
M. Merida ◽  
J. Hausfeld ◽  
...  
Keyword(s):  
Receptor Antagonist ◽  
Muscarinic Receptor ◽  
Enzyme Linked Immunosorbent Assay ◽  
Receptor Subtypes ◽  
Muscarinic Antagonists ◽  
Muscarinic Receptor Subtypes ◽  
Mucus Production ◽  
Glandular Secretion ◽  
M3 Receptor

Mucus glycoproteins (MGP) are high-molecular-weight glycoconjugates that are released from submucosal glands and epithelial goblet cells in the respiratory tract. Muscarinic receptors have an important role in the regulation of human nasal glandular secretion and mucus production, but it is not known which of the five muscarinic receptor subtypes are involved. The effect of nonselective and M1-, M2-, and M3-selective muscarinic antagonists on methacholine (MCh)-induced MGP secretion from human nasal mucosal explants was tested in vitro. MGP was assayed by enzyme-linked immunosorbent assay using a specific anti-MGP monoclonal antibody (7F10). MCh (100 microM) induced MGP secretion up to 127% compared with controls. MCh-induced MGP release was significantly inhibited by atropine (100 microM), the M, receptor antagonist pirenzepine (10–100 microM), and the M3 receptor antagonist 4-diphenylacetoxy-N-methylpiperidine methiodide (4-DAMP; 1–100 microM). 4-DAMP significantly inhibited MCh-induced MGP release at a lower concentration (1 microM) than pirenzepine (10 microM). The M2 receptor antagonists AF-DX 116 and gallamine (both at 100 microM) had no effect. No antagonist alone had a significant effect on MGP release. These results indicate that the M1 and M3 muscarinic receptor subtypes regulate MGP secretion from human nasal mucosa and suggest that the M3 receptor has the predominant effect.

scholarly journals Role of NKCC in BK channel-mediated net K+ secretion in the CCD

2011 ◽  
Vol 301 (5) ◽  
pp. F1088-F1097 ◽  
Author(s):  
Wen Liu ◽  
Carlos Schreck ◽  
Richard A. Coleman ◽  
James B. Wade ◽  
Yubelka Hernandez ◽  
...  
Keyword(s):  
Collecting Duct ◽  
Bk Channels ◽  
Bk Channel ◽  
Taqman Assay ◽  
Specific Cell ◽  
Cortical Collecting Duct ◽  
Ph Indicator ◽  
Transport Pathway ◽  
K Secretion

Apical SK/ROMK and BK channels mediate baseline and flow-induced K secretion (FIKS), respectively, in the cortical collecting duct (CCD). BK channels are detected in acid-base transporting intercalated (IC) and Na-absorbing principal (PC) cells. Although the density of BK channels is greater in IC than PC, Na-K-ATPase activity in IC is considered inadequate to sustain high rates of urinary K secretion. To test the hypothesis that basolateral NKCC in the CCD contributes to BK channel-mediated FIKS, we measured net K secretion ( JK) and Na absorption ( JNa) at slow (∼1) and fast (∼5 nl·min−1·mm−1) flow rates in rabbit CCDs microperfused in vitro in the absence and presence of bumetanide, an inhibitor of NKCC, added to the bath. Bumetanide inhibited FIKS but not basal JK, JNa, or the flow-induced [Ca2+]i transient necessary for BK channel activation. Addition of luminal iberiotoxin, a BK channel inhibitor, to bumetanide-treated CCDs did not further reduce JK. Basolateral Cl removal reversibly inhibited FIKS but not basal JK or JNa. Quantitative PCR performed on single CCD samples using NKCC1- and 18S-specific primers and probes and the TaqMan assay confirmed the presence of the transcript in this nephron segment. To identify the specific cell type to which basolateral NKCC is localized, we exploited the ability of NKCC to accept NH4+ at its K-binding site to monitor the rate of bumetanide-sensitive cytosolic acidification after NH4+ addition to the bath in CCDs loaded with the pH indicator dye BCECF. Both IC and PC were found to have a basolateral bumetanide-sensitive NH4+ entry step and NKCC1-specific antibodies labeled the basolateral surfaces of both cell types in CCDs. These results suggest that BK channel-mediated FIKS is dependent on a basolateral bumetanide-sensitive, Cl-dependent transport pathway, proposed to be NKCC1, in both IC and PC in the CCD.

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