Modulation of vasopressin action by reducing agents in Bufo marinus

1982 ◽  
Vol 243 (1) ◽  
pp. C52-C61 ◽  
Author(s):  
D. E. Butkus ◽  
J. H. Schwartz
Keyword(s):  
Adenylate Cyclase ◽  
Water Flow ◽  
Water Permeability ◽  
Regulatory Protein ◽  
Inhibitory Effect ◽  
Bufo Marinus ◽  
Inhibitory Effects ◽  
Thiol Compounds ◽  
Osmotic Water ◽  
Osmotic Water Flow

The effects of the reducing agent dithiothreitol (DTT) on vasopressin (AVP)-stimulated osmotic water flow and adenylate cyclase activity were studied in the urinary bladder of Bufo marinus. DTT produced concentration-dependent inhibition of the hydroosmotic water permeability response to 10 mU/ml AVP and 10 mM theophylline but did not inhibit the response to 10 mM adenosine 3',5'-cyclic monophosphate (cAMP). The inhibitory effects of DTT on AVP responsiveness were partially reversed by washing in DTT-free Ringer solution or by addition of oxidizing agents such as dehydroascorbic acid (DHA) or H2O2. The inhibitory effects of DTT were completely reversed by washing in DTT-free Ringer plus addition of DHA. In addition, the inhibitory effects of DTT on AVP-induced osmotic water flow were partially reversed by the GTP analogue 5'-guanylyl imidodiphosphate [Gpp(NH)p]. DTT also inhibited the adenylate cyclase response to AVP but did not alter the response to AVP plus Gpp(NH)p or the response to NaF. These observations suggest that the inhibitory effect of thiol compounds on AVP responsiveness may be modulated through alterations of a redox system distal to the hormone receptor but proximal to the catalytic subunit of adenylate cyclase. Inasmuch as Gpp(NH)p partially reversed the inhibitory effects of DTT on AVP-stimulated osmotic water permeability and prevented the inhibitory effect of DTT on AVP-stimulated adenylate cyclase, an effect on either GTPase or binding of GTP to the regulatory protein of adenylate cyclase is suggested by these observations.

Evidence for transcellular osmotic water flow in rat proximal tubules

1985 ◽  
Vol 249 (1) ◽  
pp. F124-F131 ◽  
Author(s):  
P. A. Preisig ◽  
C. A. Berry
Keyword(s):  
Surface Area ◽  
Water Flow ◽  
Water Permeability ◽  
Channel Length ◽  
Osmotic Gradient ◽  
Osmotic Water Permeability ◽  
Osmotic Water ◽  
Major Route ◽  
Osmotic Water Flow

To determine the predominant pathway for transepithelial osmotic water flow, the transepithelial osmotic water permeability [Pf(TE)] and the apparent dimensions of paracellular pores and slits were determined in rat proximal convoluted tubules microperfused in vivo. To measure Pf(TE), tubules were perfused with a hyposmotic, cyanide-containing solution. Pf(TE), calculated from the observed volume flux in response to the measured log mean osmotic gradient, was 0.12-0.15 cm/s, assuming sigmaNaCl equal to 1.0-0.7, respectively. The dimensions of the paracellular pathways were determined using measured sucrose and mannitol permeabilities (nonelectrolytes confined to the extracellular space). These were 0.43 and 0.87 X 10(-5) cm/s, respectively. By using the ratio of these permeabilities, their respective free solution diffusion coefficients and molecular radii, and the Renkin equation, the radius of the nonelectrolyte-permeable pores and the total pore area/cm2 surface area/channel length were calculated to be 1.4 nm and 3.56 cm-1, respectively. Similar calculations for slits yielded a slit half-width of 0.8 nm and a total slit area/cm2 surface area/channel length of 3.16 cm-1. The osmotic water permeability of these nonelectrolyte-permeable pathways was calculated by Poiseuille's law to be 0.0018 cm/s (pores) or 0.0014 cm/s (slits), at most 2% of Pf(TE). We conclude that the nonelectrolyte-permeable pathway in the tight junctions is not the major route of transepithelial osmotic water flow in the rat proximal tubule.

Cell osmotic water permeability of isolated rabbit proximal straight tubules

1982 ◽  
Vol 242 (4) ◽  
pp. F321-F330 ◽  
Author(s):  
E. Gonzalez ◽  
P. Carpi-Medina ◽  
G. Whittembury
Keyword(s):  
Surface Area ◽  
Water Flow ◽  
Water Permeability ◽  
Permeability Coefficient ◽  
Osmotic Water Permeability ◽  
Water Permeability Coefficient ◽  
Osmotic Water ◽  
Straight Tubules ◽  
Tubular Surface ◽  
Set Up

Proximal straight tubules were dissected and mounted in a chamber with their lumina occluded. The well-stirred bath could be 95% changed within 84 ms to set up osmotic gradients (delta Coi) across the peritubular cell aspect. Volume changes (less than or equal to 10 pl/mm) were estimated from continuous records of diameter changes (error less than 0.1 micrometers). delta Coi greater than or equal to 2-3 mosM could be discerned. delta Coi values from 10 to 44 mosM were used to evaluate Posc, the cell osmotic water permeability coefficient, and extrapolated to delta Coi = 0. Posc = 25.1 (+/- 2.3) X 10(-4) cm3.s-1.osM-1.cm2 tubular surface area-1. These values are lower than those reported for Pose, the transepithelial osmotic water permeability coefficient, and become lower if corrected for the real (infolded) peritubular cell surface area. Thus, for a given osmotic difference, transcellular water flow finds a higher resistance than paracellular water flow. Experiments were also performed with delta Coi greater than 100 mosM, but interpretation of these data is difficult because of the presence of volume regulatory phenomena and other undesirable effects.

Polyclonal antibodies in study of ADH-induced water channels in frog urinary bladder

1991 ◽  
Vol 261 (3) ◽  
pp. F437-F442
Author(s):  
G. Valenti ◽  
G. Calamita ◽  
M. Svelto
Keyword(s):  
Urinary Bladder ◽  
Water Flow ◽  
Apical Membrane ◽  
Polyclonal Antibodies ◽  
Immune Serum ◽  
Frog Urinary Bladder ◽  
Hormonal Stimulation ◽  
Osmotic Water ◽  
Triton X ◽  
Osmotic Water Flow

It is now generally accepted that changes in water permeability in anti-diuretic hormone (ADH)-responsive target epithelial cells result from the insertion in the plasma apical membrane of new components that contain channels for water. The specificity of these channels suggests that they are formed by intrinsic proteins having access to both facies and spanning the whole membrane. We have previously shown that Triton X-100 apical extracts from ADH-stimulated frog urinary bladder contain some proteins inserted under hormonal stimulation. In the present study we have developed polyclonal antibodies using Triton X-100 extract as an immunogen. After considering the inhibitory effect exerted by the whole immune serum on the osmotic water flow, we used different adsorption steps to select, from the immune serum, antibodies to apical membrane proteins inserted in response to the hormone. Immunoblot analysis of these selected antibodies shows that they recognize seven to eight proteins, of which 55-, 35-, 26-, and 17-kDa proteins are always present. Antibodies to these four proteins, affinity purified on nitrocellulose sheets, inhibited ADH-induced osmotic water flow. Altogether these results strongly suggest that proteins of 55, 35, 26, and 17 kDa (or at least one of them) are likely to be involved in the mechanism of water transport.

scholarly journals A model of electrodiffusion and osmotic water flow and its energetic structure

2011 ◽  
Vol 240 (22) ◽  
pp. 1835-1852 ◽  
Author(s):  
Yoichiro Mori ◽  
Chun Liu ◽  
Robert S. Eisenberg
Keyword(s):  
Water Flow ◽  
Osmotic Water ◽  
Osmotic Water Flow

Mechanisms of lithium-vasopressin interaction in rabbit cortical collecting tubule

1987 ◽  
Vol 252 (6) ◽  
pp. F1080-F1087 ◽  
Author(s):  
E. Cogan ◽  
M. Svoboda ◽  
M. Abramow
Keyword(s):  
Water Permeability ◽  
Regulatory Protein ◽  
Competitive Inhibitor ◽  
Inhibitory Effect ◽  
Regulatory Proteins ◽  
Collecting Tubule ◽  
Bordetella Pertussis Toxin ◽  
Guanine Nucleotide Regulatory Protein ◽  
Collecting Tubules ◽  
Stimulation Of

In single cortical collecting tubules (CCT) of the rabbit, guanosine 5'-triphosphate (GTP) increased the arginine vasopressin (AVP)-stimulated adenylate cyclase (AC) by 60% (P less than 0.05). In contrast, guanosine 5' O-(2-thio)-diphosphate (GDP-beta S), a competitive inhibitor of GTP action on the stimulatory guanine regulatory protein (Ns), reduced the AVP-stimulated AC activity by 72% (P less than 0.001), indicating the presence of endogenous GTP in the cells under study. That inhibitory effect was reversed by the addition of GTP to the incubation medium. In isolated perfused CCT, cholera toxin (CT) induced a significant increase in water permeability in the absence of AVP. In contrast, Bordetella pertussis toxin (BPT) did not modify the low AVP-independent water permeability. Lithium, an inhibitor of the hydrosmotic action of AVP, also inhibits the hydrosmotic action of CT by 70% (P less than 0.05) but not that of forskolin. The conclusions of the present study are Ns is required for AVP stimulation of AC in the CCT; Ns is functionally active in this system as evidenced by the hydrosmotic effect of CT; the lack of effect of BPT suggests that the low AVP-independent water permeability in the CCT is not the result of a tonic inhibition of the AC operating through the inhibitory guanine nucleotide regulatory protein; and the inhibition by lithium of the hydrosmotic action of AVP in the CCT appears to involve an interaction with the regulatory proteins (probably Ns) or with their binding to the catalytic unit of AC.

Anion-induced dynamic behavior of apical water channels in vasopressin-sensitive epithelia exposed to mercury

1994 ◽  
Vol 266 (6) ◽  
pp. C1577-C1585 ◽  
Author(s):  
A. Grosso ◽  
P. Jaquet ◽  
P. Brawand ◽  
R. C. De Sousa
Keyword(s):  
Dynamic Behavior ◽  
Water Flow ◽  
Water Permeability ◽  
Water Channels ◽  
Bufo Marinus ◽  
Glutaraldehyde Fixation ◽  
Experimental Conditions ◽  
Anion Effect ◽  
Channel Protein ◽  
Intracellular Chloride

We showed recently that, in toad skins preexposed to Hg, water permeability is high in SO4-Ringer and low in Cl-Ringer. This anion effect was further investigated in Hg-treated skins and bladders of toads (Bufo marinus) in a variety of experimental conditions, including glutaraldehyde fixation and stimulation by vasopressin (VP) or isoproterenol (IP). In fixed bladders either unstimulated or stimulated with VP, net water flow (Jw) in SO4-Ringer [Jw (SO4)] was always significantly higher than Jw in Cl [Jw (Cl)]; the same applies to fixed toad skins, either unstimulated or stimulated with IP. In unfixed isolated toad epidermis challenged with IP before Hg exposure, Jw(SO4)/Jw(Cl) >> 1 approaching the ratio Jw (maximally stimulated)/Jw (basal). Therefore, anion-induced Jw changes were present whether Hg acted on epithelial water channels exocytosed by Hg itself or by hydrosomotic agents and suggest a switching between open and closed configurations of the channel protein. This anion effect was not abolished by glutaraldehyde and might be correlated with changes in intracellular chloride.

Dual regulation of PTH-stimulated adenylate cyclase activity by GTP

1986 ◽  
Vol 251 (5) ◽  
pp. F858-F864 ◽  
Author(s):  
A. P. Teitelbaum ◽  
R. A. Nissenson ◽  
L. A. Zitzner ◽  
K. Simon
Keyword(s):  
Adenylate Cyclase ◽  
Pertussis Toxin ◽  
Regulatory Protein ◽  
Inhibitory Effect ◽  
Alpha Subunit ◽  
Kidney Cells ◽  
Intact Cells ◽  
Opossum Kidney ◽  
Opossum Kidney Cells ◽  
Nucleotide Regulation

Guanyl nucleotide regulation of parathyroid hormone (PTH)-activated adenylate cyclase was studied in membrane preparations of cultured opossum kidney cells. Guanosine triphosphate (GTP) (100 microM) decreased PTH-stimulated activity by 70%. Pertussis toxin enhanced PTH stimulation in intact cells and membranes, completely blocked the inhibitory effect of GTP, and catalyzed the [32P]ADP-ribosylation of a 38,000-dalton protein migrating in the position of the alpha-subunit of the inhibitory GTP-regulatory protein Ni. Cholera toxin was used to identify the alpha-subunit of the stimulatory GTP-binding protein Ns, a 42,000-dalton protein. We tested the idea that Ni may be involved in mediating the reduced response of opossum kidney cells to PTH after pretreatment with the hormone (desensitization). GTP inhibited PTH-stimulated activity to approximately the same degree in membranes from PTH-pretreated cells and control cells whether or not the cells had also received pertussis toxin. We conclude that GTP inhibits PTH action in opossum kidney cells through Ni but that PTH-induced desensitization is not mediated by Ni.

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