Cellular Mechanisms of H+and HCO3−transport in tight urinary epithelia

Al‐Awqati, Qais; Beauwens, Renaud

doi:10.1002/cphy.cp080108

Cited by 3 publications

(5 citation statements)

References 122 publications

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“…In addition to these characteristics, this clone establishes a pH gradient (H + secretion) that is stimulated by aldosterone and cAMP [12]. All these properties are characteristic of intercalated cells of the mammalian collecting duct [1,5,21].…”

Section: Discussionmentioning

confidence: 96%

Na + -independent proton secretion in MDCK-C11 cells

Fernández

Oliveira‐Souza

Malnic³

2000

Pfl�gers Archiv European Journal of Physiology

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In this work we studied the proton secretion mechanisms in recently cloned MDCK-C11 cells. We measured intracellular pH (pHi) in monolayers grown on permeable filters, using the pH-sensitive probe BCECF and an inverted epifluorescence microscope. The cells have a basal pHi of 7.20+/-0.01 (n=136) and after an acid-releasing NH4Cl pulse pHi recovered at a rate (dpHi/dt) of 0.167+/-0.006 pH units/ per minute (n=20). This rate decreased significantly when Na+ was removed from both cell surfaces, and was further reduced when they were both perfused with a solution containing no Na+ and K+. pHi recovery fell again in the presence of concanamycin (at a concentration of 4.6x10(-8) M; a specific inhibitor of the vacuolar H+-ATPase). When Na+ was removed from the apical or the basolateral side, pHi recovery (in pH units per minute) was significantly reduced to 0.099+/-0.008 (n=11) and 0.086+/-0.01 (n=10), respectively. The Na+-independent mechanism of pHi recovery was significantly inhibited by the presence of 5 x 10(-5) M Schering 28080 (an inhibitor of the H+-K+-ATPase) at the apical side (0.065+/-0.01 versus 0.099+/-0.008 pH units per minute, P<0.05), but not at the basolateral side (0.072+/-0.01 versus 0.086+/-0.01 pH units per minute). On the other hand, concanamycin inhibited the Na+-independent pHi recovery when applied apically (0.0304+/-0.005 pH units per minute, n=7) and basolaterally (0.025+/-0.004 pH units per minute, n=7). From these results we conclude that monolayers of MDCK-C11 cells have a Na+/H+ exchanger and a concanamycin-sensitive H+-ATPase on their apical and basolateral membranes; and a K+-dependent, Schering 28080-sensitive H+-K+-ATPase on their apical side.

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Section: Discussionmentioning

confidence: 96%

Na + -independent proton secretion in MDCK-C11 cells

Fernández

Oliveira‐Souza

Malnic³

2000

Pfl�gers Archiv European Journal of Physiology

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“…In the cortical and outer medullary segments of this tubule there are two cell types, principal and intercalated. Only the latter, accounting for about a third of the cells, is responsible for acid-base transport (1,2). While many nephron segments acidify their lumens, the cortical collecting tubule of rabbits usually secretes 3 Ϫ HCO .…”

Section: Introductionmentioning

confidence: 99%

Hensin, a new collecting duct protein involved in the in vitro plasticity of intercalated cell polarity.

Takito¹,

Hikita²,

Al‐Awqati³

1996

J. Clin. Invest.

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Two forms of intercalated cells are present in kidney collecting tubules, the ␣ cell has apical endocytosis, apical H ϩ -ATPase and basolateral band 3, while ␤ cells have reversed polarity of these proteins and no apical endocytosis. When a ␤ cell line was seeded at high density, it changed into the ␣ form. We previously showed that a partially purified 230 kD extracellular matrix protein of high density cells was able to retarget band 3 from apical to basolateral domains and stimulated apical endocytosis in vitro (Van Adelsberg, J., J.C. Edwards, J. Takito, B. Kiss, and Q. Al-Awqati. 1994. Cell. 76:1053-1061). We now purify this protein, which was named hensin, to near homogeneity and find that it belongs to the macrophage scavenger receptor cysteine rich (SRCR) family. An antibody, generated against a fusion protein made from a partial cDNA recognized a 230-kD protein in rabbit kidney and in the intercalated cell line.

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“…When protons are produced during a variety of metabolic reactions, they are eventually buffered by extracellular HCO 3 − . As emphasized by Al-Awqati and Beauwens, the task of the kidney in regulating acid-base balance is to regenerate the HCO 3 − (6). This is accomplished by proton secretion into the urine, which results in generation of new HCO 3 − .…”

Section: Introductionmentioning

confidence: 99%

“…This is accomplished by proton secretion into the urine, which results in generation of new HCO 3 − . An additional task of the kidney is the reabsorption of filtered HCO 3 − and this is achieved by the same process, proton secretion into the urine (6). The proximal tubule is the major segment responsible for reabsorption of filtered bicarbonate (618).…”

Section: Introductionmentioning

confidence: 99%

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Regulation of Transport in the Connecting Tubule and Cortical Collecting Duct

Staruschenko

2012

Comprehensive Physiology

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The central goal of this overview article is to summarize recent findings in renal epithelial transport, focusing chiefly on the connecting tubule (CNT) and the cortical collecting duct (CCD). Mammalian CCD and CNT are involved in fine tuning of electrolyte and fluid balance through reabsorption and secretion. Specific transporters and channels mediate vectorial movements of water and solutes in these segments. Although only a small percent of the glomerular filtrate reaches the CNT and CCD, these segments are critical for water and electrolyte homeostasis since several hormones, e.g. aldosterone and arginine vasopressin, exert their main effects in these nephron sites. Importantly, hormones regulate the function of the entire nephron and kidney by affecting channels and transporters in the CNT and CCD. Knowledge about the physiological and pathophysiological regulation of transport in the CNT and CCD and particular roles of specific channels/transporters has increased tremendously over the last two decades. Recent studies shed new light on several key questions concerning the regulation of renal transport. Precise distribution patterns of transport proteins in the CCD and CNT will be reviewed, and their physiological roles and mechanisms mediating ion transport in these segments will be also covered. Special emphasis will be given to pathophysiological conditions appearing as a result of abnormalities in renal transport in the CNT and CCD.

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Cellular Mechanisms of H⁺and HCO₃⁻transport in tight urinary epithelia

Abstract: The sections in this article are: Transepithelial Proton and Bicarbonate Transport Intercalated Cells Proton Secretion Bicarbonate Secretion Molecules Involved in Acid‐Base Transport Proton‐Translocating ATPases … Show more

Cited by 3 publications

References 122 publications

Na + -independent proton secretion in MDCK-C11 cells

Na + -independent proton secretion in MDCK-C11 cells

Hensin, a new collecting duct protein involved in the in vitro plasticity of intercalated cell polarity.

Regulation of Transport in the Connecting Tubule and Cortical Collecting Duct

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