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Wade JB, Stanton BA, Brown D. Structural Correlates of Transport in Distal Tubule and Collecting Duct Segments. Compr Physiol 2011. [DOI: 10.1002/cphy.cp080104] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Klussmann E, Maric K, Rosenthal W. The mechanisms of aquaporin control in the renal collecting duct. Rev Physiol Biochem Pharmacol 2000; 141:33-95. [PMID: 10916423 DOI: 10.1007/bfb0119577] [Citation(s) in RCA: 82] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The antidiuretic hormone arginine-vasopressin (AVP) regulates water reabsorption in renal collecting duct principal cells. Central to its antidiuretic action in mammals is the exocytotic insertion of the water channel aquaporin-2 (AQP2) from intracellular vesicles into the apical membrane of principal cells, an event initiated by an increase in cAMP and activation of protein kinase A. Water is then reabsorbed from the hypotonic urine of the collecting duct. The water channels aquaporin-3 (AQP3) and aquaporin-4 (AQP4), which are constitutively present in the basolateral membrane, allow the exit of water from the cell into the hypertonic interstitium. Withdrawal of the hormone leads to endocytotic retrieval of AQP2 from the cell membrane. The hormone-induced rapid redistribution between the interior of the cell and the cell membrane establishes the basis for the short term regulation of water permeability. In addition water channels (AQP2 and 3) of principal cells are regulated at the level of expression (long term regulation). This review summarizes the current knowledge on the molecular mechanisms underlying the short and long term regulation of water channels in principal cells. In the first part special emphasis is placed on the proteins involved in short term regulation of AQP2 (SNARE proteins, Rab proteins, cytoskeletal proteins, G proteins, protein kinase A anchoring proteins and endocytotic proteins). In the second part, physiological and pathophysiological stimuli determining the long term regulation are discussed.
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Affiliation(s)
- E Klussmann
- Forschungsinstitut für Molekulare Pharmakologie, Berlin, Germany
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Snigirevskaya ES. Structural correlates of the transepithelial water transport. INTERNATIONAL REVIEW OF CYTOLOGY 2000; 198:203-75. [PMID: 10804464 DOI: 10.1016/s0074-7696(00)98006-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
Abstract
Transepithelial permeability is one of the fundamental problems in cell biology. Epithelial cell layers protect the organism from its environment and form a selective barrier to the exchange of molecules between the lumen of an organ and an underlying tissue. This chapter discusses some problems and analyzes the participation of intercellular junctions in the paracellular transport of water, migration of intramembrane particles in the apical membrane during its permeability changes for isotonic fluid in cells of leaky epithelia, insertion of water channels into the apical membrane and their cytoplasmic sources in cells of tight epithelia under ADH (antidiuretic hormone)-induced water flows, the osmoregulating function of giant vacuoles in the transcellular fluxes of hypotonic fluid across tight epithelia, and the role of actin filaments and microtubules in the transcellular transport of water across epithelia.
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Affiliation(s)
- E S Snigirevskaya
- Institute of Cytology, Russian Academy of Sciences, St. Petersburg, Russia
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Morris RG, Tousson A, Benos DJ, Schafer JA. Microtubule disruption inhibits AVT-stimulated Cl- secretion but not Na+ reabsorption in A6 cells. THE AMERICAN JOURNAL OF PHYSIOLOGY 1998; 274:F300-14. [PMID: 9486225 DOI: 10.1152/ajprenal.1998.274.2.f300] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The effects of microtubule disruption on arginine vasotocin (AVT)-stimulated Na+ and Cl- transport were studied in A6 cells by measuring short-circuit currents (Isc) across cell layers grown in tissue culture on permeable supports. Microtubule disruption inhibited an AVT-stimulated secretory Cl- current but did not prevent activation of amiloride-sensitive Na+ transport. This AVT-stimulated secretory Cl- current was significantly inhibited by glibenclamide, an inhibitor of the cystic fibrosis transmembrane conductance regulator (CFTR). Reverse transcription of RNA isolated from A6 cells followed by polymerase chain reaction (PCR) using primers designed to amplify a portion of the R-domain of CFTR cloned from Xenopus laevis skin and immunocytochemistry demonstrated the presence of CFTR in A6 cells and an apparent recruitment of cytoplasmic CFTR to the apical cell surface after AVT stimulation. In contrast, indirect immunofluorescent labeling of Na+ channels using a polyclonal antibody raised against a biochemically isolated Na+ channel complex from bovine renal medulla labeled the apical plasma membrane but failed to demonstrate intracellular labeling of Na+ channels (except in subconfluent cells) or recruitment of Na+ channels to the apical membrane region after AVT stimulation.
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Affiliation(s)
- R G Morris
- Department of Physiology and Biophysics, University of Alabama at Birmingham 35294, USA
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Hillyard SD, Cantiello HF, Van Driessche W. K+ transport and capacitance of the basolateral membrane of the larval frog skin. THE AMERICAN JOURNAL OF PHYSIOLOGY 1997; 273:C1995-2001. [PMID: 9435506 DOI: 10.1152/ajpcell.1997.273.6.c1995] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Skin from larval bullfrogs was mounted in an Ussing-type chamber in which the apical surface was bathed with a Ringer solution containing 115 mM K+ and the basolateral surface was bathed with a Ringer solution containing 115 mM Na+. Ion transport was measured as the short-circuit current (Isc) with a low-noise voltage clamp, and skin resistance (Rm) was measured by applying a direct current voltage pulse. Membrane impedance was calculated by applying a voltage signal consisting of 53 sine waves to the command stage of the voltage clamp. From the ratio of the Fourier-transformed voltage and current signals, it was possible to calculate the resistance and capacitance of the apical and basolateral membranes of the epithelium (Ra and Rb, Ca and Cb, respectively). With SO4(2-) as the anion, Rm decreased rapidly within 5 min following the addition of 150 U/ml nystatin to the apical solution, whereas Isc increased from 0.66 to 52.03 microA/cm2 over a 60-min period. These results indicate that nystatin becomes rapidly incorporated into the apical membrane and that the increase in basolateral K+ permeability requires a more prolonged time course. Intermediate levels of Isc were obtained by adding 50, 100, and 150 U/ml nystatin to the apical solution. This produced a progressive decrease in Ra and Rb while Ca and Cb remained constant. With Cl- as the anion, Isc values increased from 2.03 to 89.57 microA/cm2 following treatment with 150 U/ml nystatin, whereas with gluconate as the anion Isc was only increased from 0.63 to 11.64 microA/cm2. This suggests that the increase in basolateral K+ permeability produced by nystatin treatment, in the presence of more permeable anions, is due to swelling of the epithelial cells of the tissue rather than the gradient for apical K+ entry. Finally, Cb was not different among skins exposed to Cl-, SO4(2-), or gluconate, despite the large differences in Isc, nor did inhibition of Isc by treatment with hyperosmotic dextrose cause significant changes in Cb. These results support the hypothesis that increases in cell volume activate K+ channels that are already present in the basolateral membrane of epithelial cells.
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Affiliation(s)
- S D Hillyard
- Department of Biological Sciences, University of Nevada, Las Vegas 89154, USA
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Tousson A, Fuller CM, Benos DJ. Apical recruitment of CFTR in T-84 cells is dependent on cAMP and microtubules but not Ca2+ or microfilaments. J Cell Sci 1996; 109 ( Pt 6):1325-34. [PMID: 8799821 DOI: 10.1242/jcs.109.6.1325] [Citation(s) in RCA: 68] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Previous studies from this laboratory have demonstrated that chloride transport induced by forskolin, but not ionomycin, in T84 cells is highly dependent on an intact microtubular network. Using an antibody raised against a region of the R domain of CFTR, we now show by indirect immunofluorescence that forskolin causes relocation of CFTR to the apical domain of T84 cells. T84 cells grown on transparent filters were incubated with agonists and/or cytoskeletal inhibitors prior to fixation, permeabilization, and staining with the antibody. A 30 second stimulation with forskolin (10 microM) caused a twofold increase in relative fluorescence intensity at the apical surface. In contrast, a 30 second exposure to ionomycin (2 microM), had no effect on the distribution of CFTR-related fluorescence. Incubation of the cells with nocodazole (33 microM), a microtubule disrupting agent, prevented the forskolin-induced rise in CFTR fluorescence at the apical surface. However, incubation of the cells with cytochalasin D, an actin inhibitor, was without effect on forskolin-related re-distribution of CFTR-associated fluorescence. In double label experiments using antibodies against both beta-tubulin and actin, CFTR-related fluorescence was found to co-localize with the microtubule network, but not with actin filaments. These observations are consistent with the microtubule-dependent acute recruitment of CFTR to the apical plasma membrane of T84 cells in response to elevations in intracellular cAMP.
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Affiliation(s)
- A Tousson
- Department of Cell Biology, University of Alabama at Birmingham 35294, USA
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Eaton DC, Becchetti A, Ma H, Ling BN. Renal sodium channels: regulation and single channel properties. Kidney Int 1995; 48:941-9. [PMID: 8569103 DOI: 10.1038/ki.1995.375] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Affiliation(s)
- D C Eaton
- Department of Physiology, Emory University School of Medicine, Atlanta, Georgia, USA
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Schwiebert EM, Gesek F, Ercolani L, Wjasow C, Gruenert DC, Karlson K, Stanton BA. Heterotrimeric G proteins, vesicle trafficking, and CFTR Cl- channels. THE AMERICAN JOURNAL OF PHYSIOLOGY 1994; 267:C272-81. [PMID: 7519398 DOI: 10.1152/ajpcell.1994.267.1.c272] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Previously (E.M. Schwiebert, N. Kizer, D. C. Gruenert, and B. A. Stanton, Proc. Natl. Acad. Sci. USA 89: 10623-10627, 1992), we showed that heterotrimeric G proteins regulate adenosine 3',5'-cyclic monophosphate (cAMP)-activated cystic fibrosis transmembrane conductance regulator (CFTR) Cl- channels in human airway epithelial cells. The goal of the present study was to test the hypothesis that heterotrimeric G proteins regulate vesicle trafficking and exocytosis and that these events are critical for cAMP activation of CFTR-mediated Cl- secretion. We report that cAMP stimulates exocytosis and CFTR Cl- conductance (GCl) in normal but not in CF cells. Stimulation of the heterotrimeric G protein G alpha i-2 inhibited cAMP-activated CFTR GCl and exocytosis in normal cells. In contrast, inhibition of G alpha i-2 stimulated exocytosis and allowed cAMP to stimulate CFTR GCl in cells isolated from patients with cystic fibrosis (CF). Brefeldin A and nocodazol prevented cAMP-induced exocytosis and also blocked cAMP stimulation of CFTR GCl in normal airway epithelial cells. Our studies suggest that the heterotrimeric G protein G alpha i-2 regulates CFTR GCl in human airway epithelial cells by modulating vesicle trafficking and the delivery of CFTR Cl- channels from an intracellular vesicular pool to the plasma membrane. Inhibition of G alpha i-2 may be a useful therapeutic approach to target mutant delta F508 CFTR Cl- channels from an intracellular vesicular pool to the plasma membrane and thereby correct defective Cl- secretion in CF airway epithelial cells.
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Affiliation(s)
- E M Schwiebert
- Department of Physiology, Dartmouth Medical School, Hanover, New Hampshire 03755
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Fuller CM, Bridges RJ, Benos DJ. Forskolin- but not ionomycin-evoked Cl- secretion in colonic epithelia depends on intact microtubules. THE AMERICAN JOURNAL OF PHYSIOLOGY 1994; 266:C661-8. [PMID: 8166229 DOI: 10.1152/ajpcell.1994.266.3.c661] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Several transport proteins are known to be trafficked to the cell membrane in response to appropriate secretagogues. In several cases, the response has been shown to be dependent on the cytoskeleton. We tested the hypothesis that the forskolin- and/or ionomycin-sensitive Cl- secretory response in colonic epithelia is dependent on an intact cytoskeleton. Using 125I- efflux as an assay for Cl- transport in the colonic epithelial cell line T84, we found that preincubation of the tissue for 3 h with either of two inhibitors of microtubule polymerization, nocodazole or colchicine, disrupted the cellular tubulin architecture and also reduced the forskolin- but not the ionomycin-evoked I- efflux. In contrast, brief exposure (4 min) to nocodazole was without effect on the forskolin-sensitive efflux, suggesting that the drug is not acting to block the stimulus-response pathway. An inactive structural analogue of colchicine, beta-lumicolchicine, had no inhibitory effect on either the forskolin-sensitive efflux or on microtubular structure. In a second model of Cl- secretion, the stripped rat colon, both colchicine and nocodazole reduced the forskolin-dependent short-circuit current by an average of 30-40%, suggesting a similar mechanism for insertion of Cl- channels into the plasma membrane. These findings suggest that the Cl- secretory response is dependent on microtubules and has a physiological role in the adenosine 3',5'-cyclic monophosphate-dependent, but not the Ca(2+)-dependent, Cl- secretion in colonic epithelia.
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Affiliation(s)
- C M Fuller
- Department of Physiology and Biophysics, University of Alabama at Birmingham 35294
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Schafer JA, Reeves WB, Andreoli TE. Mechanisms of Fluid Transport Across Renal Tubules. Compr Physiol 1992. [DOI: 10.1002/cphy.cp080115] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Baker CA, Hillyard SD. Capacitance, short-circuit current and osmotic water flow across different regions of the isolated toad skin. J Comp Physiol B 1992; 162:707-13. [PMID: 1494029 DOI: 10.1007/bf00301620] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The amphibian antidiuretic hormone, arginine vasotocin, stimulated osmotic water flow across isolated skin from the pelvic but not the pectoral skin of the toad, Bufo woodhouseii. Changes in the apical membrane capacitance were not observed for either region of the skin following treatment with arginine vasotocin when there was an osmotic gradient across the tissue. In the absence of an osmotic pressure gradient, the apical membrane capacitance of the pelvic skin increased from 2.8 +/- 0.5 to 3.3 +/- 0.6 microF.cm-2 after treatment with 5 x 10(-8) M arginine vasotocin. Under these conditions, apical membrane capacitance of the pectoral skin was 1.8 +/- 0.1 microF.cm-2 and did not change significantly after arginine vasotocin treatment. The amiloride-sensitive short-circuit current across the pelvic skin was stimulated by arginine vasotocin as was the density of channels in the apical membrane as determined by fluctuation analysis. Values for channel density in the pelvic skin also correlated with apical membrane capacitance and increased from 90 to 273 channels per micron2 of estimated membrane area following arginine vasotocin treatment. In the pectoral skin the stimulation of short-circuit current following arginine vasotocin treatment was small and an increase in channel density could not be demonstrated. The current through single Na+ channels in both regions of the skin did not different either before or after arginine vasotocin treatment.
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Affiliation(s)
- C A Baker
- Department of Biological Sciences, University of Nevada, Las Vegas 89154
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Lewis SA, Clausen C, Wills NK. Transport-related modulation of the membrane properties of toad urinary bladder epithelium. BIOCHIMICA ET BIOPHYSICA ACTA 1991; 1070:99-110. [PMID: 1661156 DOI: 10.1016/0005-2736(91)90151-w] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Impedance analysis and transepithelial electrical measurements were used to assess the effects of the apical membrane Na+ channel blocker amiloride and anion replacement on the apical and basolateral membrane conductances and areas of the toad urinary bladder (Bufo marinus). Mucosal amiloride addition decreased both apical and basolateral membrane conductances (Ga and Gbl, respectively) with no change in membrane capacitances (Ca and Cbl). Consequently, the specific conductances of these membranes decreased without significant changes in membrane area. Following amiloride removal, an increase was obtained in the steady-state rate of sodium transport compared to values before amiloride addition. This increase was independent of the initial transport rate, suggesting activation of a quiescent pool of apical sodium channels. Chloride replacement by acetate or gluconate had no significant effects on apical or basolateral membrane capacitances. The effects of these replacements on membrane conductances depended on the anion species. Gluconate (which induces cell shrinkage) decreased both membrane conductances. In contrast, acetate (which induces cell swelling) increased Ga and had no effect on Gbl. The increase in the apical membrane conductance was due to an increase in the amiloride-sensitive Na+ conductance of this membrane. In summary, mucosal amiloride addition or chloride replacements led to changes in membrane conductances without significant effects on net membrane areas.
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Affiliation(s)
- S A Lewis
- Department of Physiology, University of Texas, Medical Branch, Galveston 77550
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Lippe C, Ardizzone C. Permeability properties of the Bufo bufo bladder as affected by isoprenaline and vasopressin. ARCHIVES INTERNATIONALES DE PHYSIOLOGIE ET DE BIOCHIMIE 1989; 97:537-43. [PMID: 2483813 DOI: 10.3109/13813458909075085] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Isoprenaline, a beta adrenergic agonist, strongly increases both transepithelial fluxes across the urinary bladder of Bufo bufo; this effect is dose dependent, 10(-6)M being necessary for the maximal action. This effect is less selective than that of vasopressin: the ratio J urea/J thiourea is 3.8 under isoprenaline and 30.4 under vasopressin treatment. Both hormones differently affect the permeability of a mainly liposoluble molecule, i.e. antipyrine: vasopressin increases antipyrine permeability, while isoprenaline decreases it. Moreover diethylpyrocarbonate treatment of the luminal membrane strongly inhibits vasopressin effect on urea permeability leaving unmodified that of isoprenaline. However, the actions of both hormones are not additive. These results allows to assume that the tissue has a feedback mechanism which inhibits other hormonal action while the bladder is stimulated by a particular hormone.
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Affiliation(s)
- C Lippe
- Institute of General Physiology, University of Bari, Italy
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Silver RB, Palmer LG. 8-BrcAMP-induced capacitance and transport of H2O and Na in skin and urinary bladder of urodele amphibians. THE AMERICAN JOURNAL OF PHYSIOLOGY 1989; 256:C1145-52. [PMID: 2735392 DOI: 10.1152/ajpcell.1989.256.6.c1145] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The effects of 8-bromoadenosine 3',5'-cyclic monophosphate (8-BrcAMP) on capacitance (C), osmotic water flow (Jv), and amiloride-sensitive short-circuit current (INa) were studied in bladder and skin derived from the tiger salamander (aquatic and postmetamorphosed terrestrial phase). 8-BrcAMP-dependent increases in C, measured from the transepithelial voltage response to constant current pulses, occurred in aquatic (delta C = 44%) and terrestrial (delta C = 61%) bladders and terrestrial skin (delta C = 19%). Jv (200-mosM gradient, mucosal side hypotonic) was observed in the bladders and was further enhanced by addition of 8-BrcAMP [10(-3) M; delta Jv = 0.42 microliter.min-1.microF-1 (aquatic) and 0.32 microliter.min-1.microF-1 (terrestrial)]. The aquatic and terrestrial skins were relatively impermeable to water, but the terrestrial skin showed a small response to 8-BrcAMP (delta Jv = 0.04 microliter.min-1.microF-1). 8-BrcAMP-mediated natriferic responses were observed in aquatic bladder (delta INa = 62%) and terrestrial skin (delta INa = 105%). Antidiuretic hormone (ADH)-induced Jv was also observed in the aquatic bladder (delta Jv = 0.33 microliter.min-1.microF-1) and was similar to the 8-BrcAMP-mediated Jv measured in this tissue. The terrestrial bladder displayed a more vigorous response to 8-BrcAMP than to ADH (delta JvADH = 0.09 microliter.min-1.microF-1 and delta Jv8-BrcAMP = 0.32 microliter.min-1.microF-1), suggesting that diminished sensitivity to ADH accompanies the transition from water to land in this species.
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Affiliation(s)
- R B Silver
- Department of Physiology, Cornell University Medical College, New York, New York 10021
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Affiliation(s)
- W J Els
- Department of Anatomy and Cell Biology, University of Cape Town Medical School, Observatory, South Africa
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Krattenmacher R, Fischer H, van Driessche W, Clauss W. Noise analysis of cAMP-stimulated Na current in frog colon. Pflugers Arch 1988; 412:568-73. [PMID: 2850532 DOI: 10.1007/bf00583756] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The effects of oxytocin and cAMP on the electrogenic Na+-transport in the short-circuited epithelium of the frog colon (Rana esculenta, Rana temporaria) were investigated. Oxytocin (100 mU.ml-1) elevated the short-circuit current (Isc) transiently by 70% whereas cAMP (1 mmol.l-1) elicited a comparable sustained response. The mechanism of the natriferic action of cAMP was studied by analysing current fluctuations through apical Na+-channels induced by amiloride or CDPC (6-chloro-3,5-diaminopyrazine-2-carboxamid). The noise data were used to calculate Na+-channel density (M) and single apical Na+-current (iNa). iNa-Values obtained with amiloride and CDPC were 1.0 +/- 0.1 pA (n = 5) and 1.1 +/- 0.2 pA (n = 6) respectively and unaffected by cAMP. On the other hand, cAMP caused a significant increase in M from 0.23 +/- 0.08 micron-2 (n = 5) to 0.49 +/- 0.17 micron-2 (n = 5) in the amiloride experiments. In our studies with CDPC we obtained smaller values for M in control (0.12 +/- 0.04 micron-2; n = 6) as well as during cAMP treatment (0.19 +/- 0.06 micron-2; n = 6). However, the cAMP-induced increase in M was also significant. We conclude that cAMP stimulates Na+-transport across the frog colon by activating "silent" apical Na+-channels. Thus, the mechanism of regulation of colonic Na-transport in frogs differs considerably from that in other vertebrates as mammals and birds.
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Wade JB, Kachadorian WA. Cytochalasin B inhibition of toad bladder apical membrane responses to ADH. THE AMERICAN JOURNAL OF PHYSIOLOGY 1988; 255:C526-30. [PMID: 3140672 DOI: 10.1152/ajpcell.1988.255.4.c526] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The possible role of actin microfilaments in antidiuretic hormone (ADH)-induced increases in apical membrane water permeability was investigated in studies that evaluate inhibition by cytochalasin B of both permeability and membrane structural responses in the toad urinary bladder. Experiments were carried out in the absence of a transepithelial osmotic gradient to eliminate possible flow-induced distortions of the response. Measurements of osmotic water permeability after a brief tissue fixation with glutaraldehyde show that cytochalasin B reduces the permeability response to ADH by approximately one-third. Freeze-fracture electron microscopy indicates that the intramembrane particle aggregates, previously found to correlate closely with ADH-induced permeability, are reduced by about the same extent (28%) under these conditions. However, the frequency of apical membrane fusion events was not affected by cytochalasin B treatment. These results suggest that cytochalasin B treatment in the absence of an osmotic gradient alters the ADH-induced permeability through an effect on apical membrane aggregate frequency.
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Affiliation(s)
- J B Wade
- Department of Physiology, University of Maryland School of Medicine, Baltimore 21201
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Harris HW, Handler JS. The role of membrane turnover in the water permeability response to antidiuretic hormone. J Membr Biol 1988; 103:207-16. [PMID: 3054115 DOI: 10.1007/bf01993980] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Affiliation(s)
- H W Harris
- Division of Nephrology, Children's Hospital, Boston, Massachusetts 02115
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Van Driessche W, Erlij D. Activation of K+ conductance in basolateral membrane of toad urinary bladder by oxytocin and cAMP. THE AMERICAN JOURNAL OF PHYSIOLOGY 1988; 254:C816-21. [PMID: 2837095 DOI: 10.1152/ajpcell.1988.254.6.c816] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
We incubated toad urinary bladders with Na+-free, isotonic K+ solutions on the apical side and increased the cationic conductance of the apical membrane with nystatin (150 U/ml). Under these conditions, the short-circuit current is mostly carried by K+ flowing from mucosa to serosa. Impedance measurements showed that in nystatin-treated preparations, the electrical behavior of the tissue is dominated by the basolateral membrane properties. Oxytocin (0.1 U/ml) produced an increase of the current and the conductance of the basolateral membrane. Both the resting and the oxytocin-stimulated current were rapidly and reversibly blocked by serosal Ba2+. Addition of the adenosine 3',5'-cyclic monophosphate (cAMP) analogue [8-(4-chloropheylthio)-cAMP] to the basolateral solution mimicked the effects of oxytocin. These results show that oxytocin and cAMP stimulate a potassium conductance in the basolateral membrane and that the stimulation is not related to an increase in sodium entry through the apical membrane. Addition of ouabain (10(-3) M) to the serosal solution did not modify the stimulation by oxytocin, indicating that the activated pathway is not linked to the rate of turnover of the Na+ pump.
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Affiliation(s)
- W Van Driessche
- Laboratorium voor Fysiologie, Campus Gasthuisberg, Leuven, Belgium
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Krattenmacher R, Clauss W. Electrophysiological analysis of sodium-transport in the colon of the frog (Rana esculenta). Modulation of apical membrane properties by antidiuretic hormone. Pflugers Arch 1988; 411:606-12. [PMID: 2457866 DOI: 10.1007/bf00580855] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Sodium transport and apical bioelectrical membrane properties were investigated in frog colonic epithelium in the absence and presence of the antidiuretic hormone arginine-vasotocin (AVT). Apical Na-permeability and intracellular Na-activity were evaluated by analysis of current-voltage relationships in the serosally K-depolarized tissue. Tissue- and apical membrane capacitance were measured by voltages step analysis. The frog colon was found to be a tight epithelium with a transepithelial resistance of 2.63 +/- 0.25 k omega.muF (n = 17). 85-90% of short circuit current (11.2 +/- 1.1 microA.microF.l-1; n = 17) was related to electrogenic Na-transport from mucosa to serosa. Graded doses of amiloride (less than 50 mumol.l-1) induced Michaelis-Menten-type inhibition kinetics. Serosal addition of 10(-6) mol.l-1 AVT induced a significant increase in sodium current (25%), apical sodium permeability (19%) and tissue capacitance (4.3%) whereas intracellular Na-activity remained unchanged. There was a good correlation between increased Na-current and apical Na-permeability. No correlation was found between Na-current and membrane capacitance. Our results demonstrate that in contrast to other species the amphibian colon shows a natriferic reaction to AVT. We suggest that the regulation of Na-transport in frog colon is similar to that in the toad urinary bladder. It is caused by an activation of preexisting apical Na-channels and not by fusion of subapical cytoplasmic vesicles with the apical membrane.
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Affiliation(s)
- R Krattenmacher
- Institut für Veterinär-Physiologie, Freie Universität Berlin
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Masur SK, Massardo S. ADH and phorbol ester increase immunolabeling of the toad bladder apical membrane by antibodies made to granules. J Membr Biol 1987; 96:193-8. [PMID: 3612764 DOI: 10.1007/bf01869301] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Polyclonal antibodies were raised to isolated toad bladder granules. On immunoblots, the anti-granule antiserum specifically stained components of isolated granules. Immunocytochemically, the anti-granule antiserum labeled the apical surface of the bladder. Immunolabeling increased at the apical surface when the bladder was exposed to antidiuretic hormone (ADH) serosally or phorbol ester (PMA) mucosally--conditions which stimulate apical granule exocytosis. The increase in granule epitopes on the apical surface was sixfold greater than the net increase in surface area.
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Ardizzone C, Margiotta M, Lippe C. Action of forskolin on non-electrolyte permeability across the frog skin as compared to that of vasopressin and isoprenaline. ARCHIVES INTERNATIONALES DE PHYSIOLOGIE ET DE BIOCHIMIE 1987; 95:105-12. [PMID: 2444177 DOI: 10.3109/13813458709104522] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Forskolin, a natural diterpene activating the adenyl cyclase in a receptor-independent manner, increases symmetrically both transepithelial fluxes of urea and erithrytol through the frog skin. The effect is dose-dependent, being 5 X 10(-6) M the dose necessary to obtain the maximal action. Forskolin-induced permeabilization is inversely proportional to the molecular weight of water soluble molecules (urea greater than erythritol greater than mannitol); also the permeability of a mainly lipid soluble molecule, i.e. antipyrine, is slightly increased by the diterpene. The permeability pattern is more similar to that induced by isoprenaline as compared to that elicited by vasopressin. Differently from what occurs in other tissues, small doses of forskolin (10(-8) M) are unable to potentiate the actions of vasopressin and isoprenaline on urea permeability across the frog skin. Moreover, the maximal action of forskolin is not additive with the maximal ones of isoprenaline and vasopressin.
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Affiliation(s)
- C Ardizzone
- Institute of General Physiology, University of Bari, Italy
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Harris HW, Murphy HR, Willingham MC, Handler JS. Isolation and characterization of specialized regions of toad urinary bladder apical plasma membrane involved in the water permeability response to antidiuretic hormone. J Membr Biol 1987; 96:175-86. [PMID: 3599066 DOI: 10.1007/bf01869243] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Antidiuretic hormone (ADH) increases the apical (external facing) membrane water permeability of granular cells that line the toad urinary bladder. In response to ADH, cytoplasmic vesicles called aggrephores fuse with the apical plasma membrane and insert particle aggregates which are visualized by freeze-fracture electron microscopy. Aggrephores contain particle aggregates within their limiting membranes. It is generally accepted that particle aggregates are or are related to water channels. High rates of transepithelial water flow during ADH stimulation and subsequent hormone removal decrease water permeability and cause the endocytosis of apical membrane and aggrephores which retrieve particle aggregates. We loaded the particle aggregate-rich endocytic vesicles with horseradish peroxidase (HRP) during ADH stimulation and removal. Epithelial cells were isolated and homogenized, and a subcellular fraction was enriched for sequestered HRP obtained. The HRP-enriched membrane fraction was subjected to a density shifting maneuver (Courtoy et al., J. Cell Biol. 98:870, 1984), which yielded a purified membrane fraction containing vesicles with entrapped HRP. The density shifted vesicles were composed of approximately 20 proteins including prominent species of 55, 17 and 7 kD. Proteins of these molecular weights appear on the apical surface of ADH-stimulated bladders, but not the apical surface of control bladders. Therefore, we believe these density shifted vesicles contain proteins involved in the ADH-stimulated water permeability response, possibly components of particle aggregates and/or water channels.
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Wills NK, Clausen C. Transport-dependent alterations of membrane properties of mammalian colon measured using impedance analysis. J Membr Biol 1987; 95:21-35. [PMID: 3560207 DOI: 10.1007/bf01869627] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Direct current (DC) measurement methods have been commonly used to characterize the conductance properties of the mammalian colon. However, these methods provide no information concerning the effects of tissue morphology on the electrophysiological properties of this epithelium. For example, distribution of membrane resistances along narrow fluid-filled spaces such as the lateral intercellular spaces (LIS) or colonic crypts can influence DC measurements of apical and basolateral membrane properties. We used impedance analysis to determine the extent of such distributed resistance effects and to assess the conductance and capacitance properties of the colon. Because capacitance is proportional to membrane area, this method provides new information concerning membrane areas and specific ionic conductances for these membranes. We measured transepithelial impedance under three conditions: control conditions in which the epithelium was open-circuited and bathed on both sides with NaCl-HCO3 Ringer's solutions, amiloride conditions which were similar to control except that 100 microM amiloride was present in the mucosal bathing solution, and mucosal NaCl-free conditions in which mucosal Na and Cl were replaced by potassium and sulfate or gluconate ("K+ Ringer's"). Three morphologically-based equivalent circuit models were used to evaluate the data: a lumped model (which ignores LIS resistance), a LIS distributed model (distributed basolateral membrane impedance) and a crypt-distributed model (distributed apical membrane impedance). To estimate membrane impedances, an independent measurement of paracellular conductance (Gs) was incorporated in the analysis. Although distributed models yielded improved fits of the data, the distributed and lumped models produced similar estimates of membrane parameters. The predicted effects of distributed resistances on DC microelectrode measurements were largest for the LIS-distributed model. LIS-distributed effects would cause a 12-15% underestimate of membrane resistance ratio (Ra/Rb) for the control and amiloride conditions and a 34% underestimate for the "K Ringer's" condition. Distributed resistance effects arising from the crypts would produce a 1-2% overestimate of Ra/Rb. Apical and basolateral membrane impedances differed in the three different experimental conditions. For control conditions, apical membrane capacitance averaged 21 microF/cm2 and the mean apical membrane specific conductance (Ga-norm) was 0.17 mS/microF. The average basolateral membrane capacitance was 11 microF/cm2 with a mean specific conductance (Gb-norm) of 1.27 mS/microF.(ABSTRACT TRUNCATED AT 400 WORDS)
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Van Driessche W, Aelvoet I, Erlij D. Oxytocin and cAMP stimulate monovalent cation movements through a Ca2+-sensitive, amiloride-insensitive channel in the apical membrane of toad urinary bladder. Proc Natl Acad Sci U S A 1987; 84:313-7. [PMID: 2432608 PMCID: PMC304194 DOI: 10.1073/pnas.84.1.313] [Citation(s) in RCA: 33] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The effects of oxytocin and cAMP on ion transport were investigated in toad urinary bladders incubated with Ca2+-free solutions on the apical side. Under these conditions both oxytocin and cAMP markedly stimulated the movements of Na+, K+, Rb+, Cs+, Li+, and NH4+ through a pathway that is insensitive to amiloride. The amiloride-insensitive currents were inhibited by the addition of Ca2+, Sr2+, or Mg2+ to the apical solution. The movement of the monovalent cations was associated with a spontaneous Lorentzian component in the power spectrum of the fluctuation in short-circuit current. The plateau of the Lorentzian component was enhanced by oxytocin and cAMP and was depressed by divalent cations. Methohexital inhibited the stimulation of monovalent cation movements caused by oxytocin. These findings suggest that oxytocin and cAMP activate at least two kinds of ionic channels in the apical membrane of toad urinary bladder: the well-known amiloride-sensitive channel and an amiloride-insensitive channel that allows the movement of several monovalent cations and is blocked by Ca2+ and other divalent cations.
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Garvin JL, Simon SA, Cragoe EJ, Mandel LJ. Binding of 3H-phenamil, an irreversible amiloride analog, to toad urinary bladder: effects of aldosterone and vasopressin. J Membr Biol 1986; 90:107-13. [PMID: 2425092 DOI: 10.1007/bf01869928] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Phenamil, an analog of amiloride, has previously been shown to bind specifically to sodium channels in toad bladder (J.L. Garvin et al., J. Membrane Biol. 87:45-54, 1985). In this paper, 3H-phenamil was used to measure sodium channel density in both isolated epithelial cells and intact bladders. From the specific binding to intact bladders, a channel density of 455 +/- 102 channels/micron2 was calculated. No correlation between specific binding and the magnitude of irreversible inhibition of short-circuit current was found. Pretreatment of intact bladders with 1 mg/ml trypsin reduced specific binding to isolated cells by 82 +/- 5%. In isolated cells, neither aldosterone nor vasopressin had any significant effect on specific phenamil binding. It is inferred that phenamil binds to both open and closed channels which may be either in the mucosal membrane or in the submembrane space. Finally, and rather surprisingly, we found that 3H-phenamil binds irreversibly to the basolateral membrane at concentrations as low as 4 X 10(-7) M. Therefore, care must be used in interpreting binding studies with amiloride or its analog at such concentrations.
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Kempson SA, Dousa TP. Current concepts of regulation of phosphate transport in renal proximal tubules. Biochem Pharmacol 1986; 35:721-6. [PMID: 3513766 DOI: 10.1016/0006-2952(86)90237-6] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The wealth of new information on BBM transport of Pi which has accumulated in recent years gives an indication of the importance and intellectual challenge that the mechanism of this process poses to investigators. In this brief reflection on the field, we have tried to draw attention to some general principles and features which may be helpful as working hypotheses in the development of the field. To date, a disproportionate amount of effort may have been spent on deciphering putative intracellular regulatory mechanisms, without knowing some essential fundamental properties of the Na+-Pi-COT. We suggest that a major effort should be exerted towards elucidating biogenesis of the Na+-Pi-COT, the possible existence of a membrane cycling mechanism, and a refined analysis of the Na+-Pi-COT in specific subsegments of proximal tubules. Advances in these areas together with studies of both the rapid and long-term adaptive regulation of Pi transport are needed, given the central role of the kidney in total body Pi homeostasis both in health and disease.
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Marver D. Models of aldosterone action on sodium transport: emerging concepts. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 1986; 196:153-71. [PMID: 3012976 DOI: 10.1007/978-1-4684-5101-6_11] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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Lewis SA, de Moura JL. Apical membrane area of rabbit urinary bladder increases by fusion of intracellular vesicles: An electrophysiological study. J Membr Biol 1984; 82:123-36. [PMID: 6542593 DOI: 10.1007/bf01868937] [Citation(s) in RCA: 67] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Mammalian urinary bladder undergoes, in a 24-hour period, a series of slow fillings and rapid emptying. In part the bladder epithelium accommodates volume increase by stretching the cells so as to eliminate microscopic folds. In this paper we present evidence that once the cells have achieved a smooth apical surface, further cell stretching causes an insertion of cytoplasmic vesicles resulting in an even greater apical surface area per cell and an enhanced storage capacity for the bladder. Vesicle insertion was stimulated by application of a hydrostatic pressure gradient which caused the epithelium to bow into the serosal solution. Using capacitance as a direct and nondestructive measure of area we found that stretching caused a 22% increase in area. Removal of the stretch caused area to return to within 8% of control. An alternate method for vesicle insertion was swelling the cells by reducing mucosal and serosal osmolarity. This perturbation resulted in a 74% increase in area over a 70-min period. Returning to control solutions caused area to decrease as a single exponential with an 11-min time constant. A microtubule blocking agent (colchicine) did not inhibit the capacitance increase induced by hypoosmotic solutions, but did cause an increase in capacitance in the absence of a decreased osmolarity. Microfilament disrupting agent (cytochalasin B, C.B.) inhibited any significant change in capacitance after osmotic challenge. Treatment of bladders during swelling with C.B. and subsequent return to control solutions increased the time constant of the recovery to control values (22 min). The Na+-transporting ability of the vesicles was determined and found to be greater than that of the apical membrane. Aldosterone increased the transport ability of the vesicles. We conclude that some constituent of urine causes a loss of apical membrane permeability. Using electrophysiological methods we estimated that the area of cytoplasmic vesicles is some 3.3 times that of the apical membrane area. We discuss these results in a general model for vesicle translocation in mammalian urinary bladder.
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Chapter 3 Membrane Area Changes Associated with Proton Secretion in Turtle Urinary Bladder Studied Using Impedance Analysis Techniques. ACTA ACUST UNITED AC 1984. [DOI: 10.1016/s0070-2161(08)60870-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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Lewis SA, Hanrahan JW, Driessche WV. Channels across Epithelial Cell Layers. CURRENT TOPICS IN MEMBRANES AND TRANSPORT 1984. [DOI: 10.1016/s0070-2161(08)60441-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
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Stetson DL, Steinmetz PR. Role of membrane fusion in CO2 stimulation of proton secretion by turtle bladder. THE AMERICAN JOURNAL OF PHYSIOLOGY 1983; 245:C113-20. [PMID: 6408926 DOI: 10.1152/ajpcell.1983.245.1.c113] [Citation(s) in RCA: 213] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
The changes in cell structure produced during stimulation of proton secretion by CO2 in turtle bladder were examined using ultrastructural morphometric methods. One hour after CO2 addition, the area of the luminal membrane of the carbonic anhydrase-containing (CA) cell population was increased 2.5-fold and the volume percent of electron-lucent cytoplasmic vesicles in these CA cells was decreased by 61%. No changes were observed in the epithelial granular cells. These results suggest that during CO2 stimulation the vesicles fuse with the luminal membrane. CO2 stimulation of proton secretion is inhibited by the cytoskeleton-disrupting drugs colchicine and cytochalasin B and by 99% deuterium oxide as the Ringer solvent. Deuterium oxide also inhibits the decrease in cytoplasmic vesicles. Thus stimulation of proton secretion by turtle bladder CA cells depends to a large extent on vesicle fusion and the resultant increase in luminal surface area.
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Stetson DL, Wade JB. Ultrastructural characterization of cholesterol distribution in toad bladder using filipin. J Membr Biol 1983; 74:131-8. [PMID: 6410073 DOI: 10.1007/bf01870502] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
The polyene antibiotic filipin was used to characterize the cholesterol distribution in the membranes of the toad bladder epithelium in freeze-fracture replicas. The apical membranes of granular and mitochondria-rich cells incorporate moderate amounts of filipin while the basolateral membranes of both cell types incorporate substantially greater amounts. Intracellular membranes, in general, take up very little filipin. The major exception to this is the granule membrane, which appears to be rich in cholesterol. An inverse correlation was found between the density of filipin-sterol complexes in the apical membrane and the incidence of granules in the cytoplasm. This suggests that fusion of granules with the apical membrane may be responsible for variation in the concentration of cholesterol in the apical membrane. Thirty minutes following vasopressin exposure, there is no consistent change in the cholesterol content of the apical membrane of granular cells as measured by the incidence of filipin-sterol complexes. The lack of change in the amount of membrane cholesterol indicates that the vasopressin-induced increase in transepithelial water permeability is not mediated by a change in cholesterol content of the apical membrane.
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