Effects of calcitonin on function of intercalated cells of rat cortical collecting duct

1993 ◽  
Vol 264 (2) ◽  
pp. F221-F227 ◽  
Author(s):  
E. Siga ◽  
B. Mandon ◽  
N. Roinel ◽  
C. de Rouffignac
Keyword(s):  
Collecting Duct ◽  
Disulfonic Acid ◽  
Na Channel ◽  
Adenylate Cyclase System ◽  
Cortical Collecting Duct ◽  
Osmotic Water ◽  
Acid Base Status ◽  
Hormonal Action ◽  
Specific Receptors

In the rat cortical collecting duct (CCD), the presence of highly specific receptors to calcitonin (CT) coupled to a sensitive adenylate cyclase system suggests that this segment is a target site for CT. Our aim was to explore the effects of CT on the rat CCD microperfused in vitro. The hormone failed to alter the osmotic water permeability and did not affect net Na+ transport but generated a lumen-positive transepithelial potential difference (PDte), which under control conditions was close to zero. This response was dose dependent and was still observed in the presence of luminal amiloride, despite the luminal positivity generated by the Na+ channel blocker (PDte increased from 4.0 +/- 0.8 to 9.5 +/- 1.1 mV). In contrast, the nominal absence of CO2/HCO3- or the use of a low-Cl- solution totally prevented the PDte changes caused by CT. The CT-induced lumen-positive PDte was reduced by 2.3 +/- 0.8 mV after the basolateral addition of the Cl- channel inhibitor diphenylamine-2-carboxylate. 4-Acetamido-4'-isothiocyanostilbene-2,2'-disulfonic acid and acetazolamide, which inhibit Cl-/HCO3- exchangers and carbonic anhydrase activities, respectively, also inhibited the CT-induced PDte by 4.6 +/- 0.5 and 5.0 +/- 0.9 mV. To test whether the acid-base status of the animals influences the response to CT, rats underwent an acid or alkali load. CCD dissected from acid-loaded rats responded to CT to the same extent as control animals, but the hormonal action was significantly attenuated when the CCD was harvested from alkali-loaded rats (PDte increases: acid 4.0 +/- 0.3 vs. alkali 1.6 +/- 0.6 mV, P < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Cellular actions of cAMP on HCO3(-)-secreting cells of rabbit CCD: dependence on in vivo acid-base status

1994 ◽  
Vol 266 (4) ◽  
pp. F528-F535 ◽  
Author(s):  
C. Emmons ◽  
J. B. Stokes
Keyword(s):  
Anion Exchanger ◽  
Collecting Duct ◽  
Basolateral Membrane ◽  
Disulfonic Acid ◽  
Intercalated Cells ◽  
Cortical Collecting Duct ◽  
Acid Base ◽  
Acid Base Status

HCO3- secretion by cortical collecting duct (CCD) occurs via beta-intercalated cells. In vitro CCD HCO3- secretion is modulated by both the in vivo acid-base status of the animal and by adenosine 3',5'-cyclic monophosphate (cAMP). To investigate the mechanism of cAMP-induced HCO3- secretion, we measured intracellular pH (pHi) of individual beta-intercalated cells of CCDs dissected from alkali-loaded rabbits perfused in vitro. beta-Intercalated cells were identified by demonstrating the presence of an apical anion exchanger (cell alkalinization in response to removal of lumen Cl-). After 180 min of perfusion to permit decrease of endogenous cAMP, acute addition of 0.1 mM 8-bromo-cAMP or 1 microM isoproterenol to the bath caused a transient cellular alkalinization (> 0.20 pH units). In the symmetrical absence of either Na+, HCO3-, or Cl-, cAMP produced no change in pHi. Basolateral dihydrogen 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (0.1 mM) for 15 min before cAMP addition also prevented this alkalinization. In contrast to the response of cells from alkali-loaded rabbits, addition of basolateral cAMP to CCDs dissected from normal rabbits resulted in an acidification of beta-intercalated cells (approximately 0.20 pH units). The present studies demonstrate the importance of the in vivo acid-base status of the animal in the regulation of CCD HCO3- secretion by beta-intercalated cells. The results identify the possible existence of a previously unrecognized Na(+)-dependent Cl-/HCO3- exchanger on the basolateral membrane of beta-intercalated cells in alkali-loaded rabbits.

Functional characterization of alpha- and beta-intercalated cell types in rabbit cortical collecting duct

1991 ◽  
Vol 261 (3) ◽  
pp. F377-F385 ◽  
Author(s):  
H. Furuya ◽  
M. D. Breyer ◽  
H. R. Jacobson
Keyword(s):  
Collecting Duct ◽  
Basolateral Membrane ◽  
Functional Characterization ◽  
Cell Types ◽  
Disulfonic Acid ◽  
Cortical Collecting Duct ◽  
Electrical Measurements ◽  
Collecting Ducts

Single-cell electrical measurements and spectrophotometric determinations of intracellular pH were used to determine unique features of alpha- and beta-intercalated cells (alpha-IC, beta-IC) in in vitro perfused rabbit cortical collecting ducts (CCD). pHi rose in alpha-IC and fell in beta-IC after bath Cl- removal. Luminal Cl- removal did not change pHi of alpha-IC, but pHi of beta-IC rose by 0.36 +/- 0.01 pH units. Cl- concentration-dependent recovery of beta-IC pHi revealed a Cl- Km of 18.7 mM for the luminal Cl(-) -HCO3- exchanger. Measurements of basolateral membrane voltage (Vbl) also showed two IC cell types. Removal of luminal Cl- did not change Vbl in alpha-IC, whereas Vbl hyperpolarized by a mean of 73.2 +/- 3.5 mV in beta-IC. Reducing bath Cl- depolarized both alpha- and beta-IC Vbl. In alpha-IC a large repolarization of 39.8 +/- 5.2 mV followed acute depolarization after bath Cl- removal. Reducing bath HCO3- (constant CO2) had little effect on beta-IC Vbl, whereas alpha-IC Vbl depolarized by 5.2 +/- 0.7 mV. Reducing luminal HCO3- in the absence of luminal Cl- produced a 17.6 +/- 1.8 mV depolarization in beta-IC. This change was independent of luminal Na+ and was not blocked by luminal 10(-4) M 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS). In beta-IC, Vbl was not altered by either bath or lumen DIDS in the presence of luminal Cl-. However, when luminal Cl- was removed, luminal DIDS reversibly depolarized Vbl by 9.6 +/- 2.9 mV.(ABSTRACT TRUNCATED AT 250 WORDS)

Luminal prostaglandin E2 modulates sodium and water transport in rabbit cortical collecting ducts

1995 ◽  
Vol 268 (6) ◽  
pp. F1093-F1101 ◽  
Author(s):  
Y. Ando ◽  
Y. Asano
Keyword(s):  
Prostaglandin E2 ◽  
Collecting Duct ◽  
Dependent Manner ◽  
Cortical Collecting Duct ◽  
Osmotic Water ◽  
Basolateral Side ◽  
Luminal Side ◽  
Transepithelial Voltage

We have previously found that arginine vasopressin (AVP) acts not only from the basolateral side but also from the luminal side of the rabbit cortical collecting duct (CCD). In the present study, we examined whether prostaglandin E2 (PGE2), another classic and potent modulator of the collecting duct functions, exerts luminal actions in the rabbit CCD perfused in vitro. Although luminal prostaglandin I2 was inert, luminal PGE2 (> 1 nM) induced transient hyperpolarization of transepithelial voltage followed by sustained depolarization in a dose-dependent manner. This action was preserved in the presence of basolateral PGE2, luminal AVP, or luminal BaCl2, but abolished by basolateral ouabain or luminal amiloride. Furthermore, unlike luminal AVP, luminal PGE2 suppressed Na transport and increased osmotic water permeability. The present study suggests that PGE2, similar to AVP but in a different fashion, modulates transepithelial transports from both luminal and basolateral sites in the CCD in vivo.

scholarly journals Endothelin-1 inhibits sodium reabsorption by ETA and ETB receptors in the mouse cortical collecting duct

2013 ◽  
Vol 305 (4) ◽  
pp. F568-F573 ◽  
Author(s):  
I. Jeanette Lynch ◽  
Amanda K. Welch ◽  
Donald E. Kohan ◽  
Brian D. Cain ◽  
Charles S. Wingo
Keyword(s):  
Hormonal Regulation ◽  
Collecting Duct ◽  
Early Response ◽  
Sodium Reabsorption ◽  
Na Channel ◽  
Cortical Collecting Duct ◽  
Water Excretion ◽  
Endothelin 1 ◽  
Arterial Blood

The collecting duct (CD) is a major renal site for the hormonal regulation of Na homeostasis and is critical for systemic arterial blood pressure control. Our previous studies demonstrated that the endothelin-1 gene (edn1) is an early response gene to the action of aldosterone. Because aldosterone and endothelin-1 (ET-1) have opposing actions on Na reabsorption (JNa) in the kidney, we postulated that stimulation of ET-1 by aldosterone acts as a negative feedback mechanism, acting locally within the CD. Aldosterone is known to increase JNa in the CD, in part, by stimulating the epithelial Na channel (ENaC). In contrast, ET-1 increases Na and water excretion through its binding to receptors in the CD. To date, direct measurement of the quantitative effect of ET-1 on transepithelial JNa in the isolated in vitro microperfused mouse CD has not been determined. We observed that the CD exhibits substantial JNa in male and female mice that is regulated, in part, by a benzamil-sensitive pathway, presumably ENaC. ENaC-mediated JNa is greater in the cortical CD (CCD) than in the outer medullary CD (OMCD); however, benzamil-insensitive JNa is present in the CCD and not in the OMCD. In the presence of ET-1, ENaC-mediated JNa is significantly inhibited. Blockade of either ETA or ETB receptor restored JNa to control rates; however, only ETA receptor blockade restored a benzamil-sensitive component of JNa. We conclude 1) Na reabsorption is mediated by ENaC in the CCD and OMCD and also by an ENaC-independent mechanism in the CCD; and 2) ET-1 inhibits JNa in the CCD through both ETA and ETB receptor-mediated pathways.

Sodium and water transport in cortical collecting duct of Dahl salt-resistant rat

1994 ◽  
Vol 267 (4) ◽  
pp. F583-F591 ◽  
Author(s):  
L. H. Kudo ◽  
C. T. Hawk ◽  
J. A. Schafer
Keyword(s):  
Collecting Duct ◽  
Cortical Collecting Duct ◽  
Osmotic Water Permeability ◽  
Sprague Dawley ◽  
Osmotic Water ◽  
Depot Injection ◽  
Transepithelial Voltage ◽  
Net Fluxes

Studies were conducted to determine whether the cortical collecting duct (CCD) of the Dahl salt-resistant rat (inbred Rapp strain; R/Jr) exhibits the same responses to deoxycorticosterone (DOC; 2.5 mg as a depot injection in vivo, 3-8 days before experimentation) and arginine vasopressin (AVP, 220 pM in vitro) as the Sprague-Dawley (SD) [L. Chen, S.K. Williams, and J.A. Schafer. Am. J. Physiol. 259 (Renal Fluid Electrolyte Physiol. 28): F147-F156, 1990] and Dahl salt-sensitive (inbred Rapp strain, S/Jr) [C.T. Hawk and J.A. Schafer. Am. J. Physiol. 260 (Renal Fluid Electrolyte Physiol. 29): F471-F478, 1991] CCD. Qualitatively, the R/Jr CCD responded as in the other two strains: AVP elevated the osmotic water permeability (Pf, micron/s) from 0 to approximately 1,200; either AVP or DOC, when used alone, increased the lumen-to-bath 22Na+ flux (Jl-->b, pmol.min-1.mm-1) from the control range of 20-25 to approximately 40 and hyperpolarized the transepithelial voltage. AVP and DOC effects were synergistic, elevating Jl-->b to 90 +/- 5 (mean +/- SE) with both hormones, but this value was significantly lower than observed previously in both the SD and the S/Jr CCD, 125 +/- 6 and 140 +/- 6, respectively. However, bath-to-lumen fluxes (Jb--l) were also significantly lower than observed in the SD and S/Jr CCD. Because net fluxes (Jnet) in these experiments can be determined only as nonpaired differences between unidirectional fluxes, it is uncertain whether Jnet values in the R/Jr CCD are significantly lower than in the SD or S/Jr CCD.(ABSTRACT TRUNCATED AT 250 WORDS)

Functional differentiation of cell types of cortical collecting duct

1985 ◽  
Vol 248 (3) ◽  
pp. F449-F453 ◽  
Author(s):  
R. G. O'Neil ◽  
R. A. Hayhurst
Keyword(s):  
Channel Blocker ◽  
Collecting Duct ◽  
Lectin Binding ◽  
Fluorescent Microscopy ◽  
Cell Types ◽  
Cell Swelling ◽  
K Channel ◽  
Na Channel ◽  
Cortical Collecting Duct

Interference-contrast and fluorescent microscopy were used to differentiate between the two cell types--principal cells (PC) and intercalated cells (IC)--of the isolated perfused cortical collecting duct of the rabbit. Using Hoffman Modulation Contrast optics, two types of cell outlines could be identified: "hexagonal" and "circular" profiles. To characterize the cell types further, the binding of fluorescein-labeled peanut lectin, which has been shown to be specific for the luminal cell membrane of the IC, was monitored with epifluorescent techniques. The lectin was observed to bind to the circular cell type only, confirming it as the IC. With use of the fluorescent nuclear probe acridine orange to quantitate the total number of cells per millimeter of tubule length, the fraction of ICs (lectin-binding cells) was estimated to average 29%, and the fraction of PCs (non-lectin-binding cells) to average 71% of all cells. The studies were extended to functionally separate between the two cell types by monitoring cell swelling when a lumen-to-bath current pulse was passed. Current-induced swelling was observed only in the PC and could be inhibited by the luminal addition of both the Na+ channel blocker amiloride, and the K+ channel blocker barium, thereby implicating the PC in the process of Na+ absorption and K+ secretion in this tissue. It is concluded that optical techniques can be applied to the cortical collecting duct perfused in vitro to differentiate between and study functional properties of the cell types.

Whole cell and unitary amiloride-sensitive sodium currents in M-1 mouse cortical collecting duct cells

1996 ◽  
Vol 270 (4) ◽  
pp. C998-C1010 ◽  
Author(s):  
M. L. Chalfant ◽  
T. G. O'Brien ◽  
M. M. Civan
Keyword(s):  
Collecting Duct ◽  
Cell Permeability ◽  
Na Channel ◽  
Na Channels ◽  
Cortical Collecting Duct ◽  
Ionic Selectivity ◽  
Whole Cell ◽  
Duct Cells ◽  
Excised Patches ◽  
Collecting Duct Cells

Amiloride-sensitive whole cell currents have been reported in M-1 mouse cortical collecting duct cells (Korbmacher et al., J. Gen. Physiol. 102: 761-793, 1993). We have confirmed that amiloride inhibits the whole cell currents but not necessarily the measured whole cell currents. Anomalous responses were eliminated by removing external Na+ and/or introducing paraepithelial shunts. The amiloride-sensitive whole cell currents displayed Goldman rectification. The ionic selectivity sequence of the amiloride-sensitive conductance was Li+ > Na+ >> K+. Growth of M-1 cells on permeable supports increased the amiloride-sensitive whole cell permeability, compared with cells grown on plastic. Single amiloride-sensitive channels were observed, which conformed to the highly selective low-conductance amiloride-sensitive class [Na(5)] of epithelial Na+ channels. Hypotonic pretreatment markedly slowed run-down of channel activity. The gating of the M-1 Na+ channel in excised patches was complex. Open- and closed-state dwell-time distributions from patches that display one operative channel were best described with two or more exponential terms each. We conclude that 1) study of M-1 whole cell Na+ currents is facilitated by reducing the transepithelial potential to zero, 2) these M-1 currents reflect the operation of Na(5) channels, and 3) the Na+ channels display complex kinetics, involving > or = 2 open and > or = 2 closed states.

Mechanism of bradykinin, ADH, and cAMP interaction in rabbit cortical collecting duct

1985 ◽  
Vol 249 (5) ◽  
pp. F645-F653 ◽  
Author(s):  
V. L. Schuster
Keyword(s):  
Collecting Duct ◽  
Prostaglandin Synthesis ◽  
Regulatory Subunit ◽  
Cortical Collecting Duct ◽  
Camp Generation ◽  
Osmotic Water ◽  
Transepithelial Voltage ◽  
Collecting Tubules ◽  
Prostaglandin Synthesis Inhibitors ◽  
Osmotic Water Flow

Vasopressin (ADH) and bradykinin (BK) have been shown to stimulate prostaglandin synthesis in rabbit cortical collecting tubules. We studied ADH and BK effects on osmotic water flow (Lp), Na transport (JNa), and transepithelial voltage (VT). Bath BK but not lumen BK blunted subsequent ADH hydroosmotic responses. This BK effect was prevented by ibuprofen or pertussigen pretreatment and was overcome with exogenous cAMP, suggesting that BK, via prostaglandins, interferes with ADH action on Lp at the cAMP generation step. In contrast, bath BK had no effect on bath-to-lumen (Jb-1Na) or lumen-to-bath (Jl-bNa) Na flux or on VT. As reported by others, ADH lowered Jl-bNa and depolarized VT; however, prostaglandin synthesis inhibitors neither prevented nor reversed these ADH effects. Together, these BK and ADH data do not support regulation of JNa by peptide-stimulated prostaglandins. Moreover, cAMP alone depolarized VT but had no effect on Jl-bNa. Therefore, ADH-induced depolarization of VT may at least partly owe to cAMP effects on VT independent of accompanying changes in JNa. As with Lp, bath BK blunted subsequent ADH effects on VT and, to a lesser extent, Jl-bNa; these BK effects on ADH action were also prevented by ibuprofen or pertussigen pretreatment. The data are consistent with the following model: 1) ADH depolarizes VT and increases Lp via cAMP; 2) ADH decreases JNa via neither cAMP nor prostaglandins; and 3) BK, via prostaglandins, inhibits the actions of ADH on Lp and VT at the inhibitory guanyl-nucleotide regulatory subunit of adenylate cyclase.

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.

Effect of insulin on potassium secretion in rabbit cortical collecting ducts

1992 ◽  
Vol 262 (1) ◽  
pp. F30-F35 ◽  
Author(s):  
H. Furuya ◽  
K. Tabei ◽  
S. Muto ◽  
Y. Asano
Keyword(s):  
Collecting Duct ◽  
Dependent Manner ◽  
Cortical Collecting Duct ◽  
Plasma Insulin Concentration ◽  
Concentration Dependent Manner ◽  
K Secretion ◽  
Potassium Secretion ◽  
Transepithelial Voltage ◽  
K Transport

Insulin is known to play an important role in the regulation of extrarenal K homeostasis. Previous clearance studies have shown that insulin decreases urinary K excretion, but the responsible nephron segments have not been identified. In this microperfusion study, in vitro, the effect of insulin on K transport in the cortical collecting duct (CCD), which is thought to be an important segment for regulation of the final urinary K excretion, was investigated. Basolateral insulin (10(-6) M) significantly inhibited net K secretion by 20% (mean JK = -26.2 +/- 4.2 peq.mm-1.min-1 for controls compared with -21.1 +/- 3.4 with insulin, P less than 0.001) and depolarized the transepithelial voltage (VT, from -14.6 +/- 3.5 to -10.8 +/- 3.5 mV, P less than 0.005), recovery did not occur over 60 min. Insulin (10(-11)-10(-5) M) depressed K secretion and depolarized the VT in a concentration-dependent manner. The half-maximal concentration was 5 x 10(-10) M, which is within the physiological range of plasma insulin concentration. In tubules of deoxycorticosterone acetate-treated rabbits, insulin also produced a significant fall in K secretion (from -43.4 +/- 7.5 to -36.1 +/- 5.7 peq.mm-1.min-1, P less than 0.05). Although luminal Ba (2 mM) decreased K secretion (from -14.4 +/- 2.9 to -7.0 +/- 1.7 peq.mm-1.min-1), basolateral insulin (10(-6) M) inhibited K secretion further (to -4.7 +/- 1.3 peq.mm-1.min-1, P less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

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