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  • 1
    Electronic Resource
    Electronic Resource
    Incorporation of cytoplasmic vesicles into apical membrane of mammalian urinary bladder epithelium (1982)
    [s.l.] : Nature Publishing Group
    Nature 297 (1982), S. 685-688 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Rabbit urinary bladder epithelium was-dissected, stripped of underlying muscular coats and mounted in modified Ussing chambers (2 cm2 nominal area) designed to eliminate edge damage as previously described1. Both sides of the epithelium were bathed at all times with identical solutions. Open ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/297685a0
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  • 2
    Electronic Resource
    Electronic Resource
    Active sodium transport by mammalian urinary bladder (1975)
    [s.l.] : Nature Publishing Group
    Nature 253 (1975), S. 747-748 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Sheets of rabbit urinary bladder were mounted in vitro between temperature-controlled (37 C) Plexiglass chambers with 2 cm2 exposed. The bathing solution was 110 mM NaCl, 7 mM KC1, 25 mM NaHCO3, 2 mM CaCl2, 2 mM MgSO4, 1.2 mM NaH2PO4, and 10 mM glucose, gassed with 5% CO2-95% O2 OH 7.4). Three ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/253747a0
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  • 3
    Electronic Resource
    Electronic Resource
    LOCALIZATION OF THE ALDOSTERONE RESPONSE IN RABBIT URINARY BLADDER BY ELECTROPHYSIOLOGICAL TECHNIQUES (1981)
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 372 (1981), S. 0 
    Details
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1749-6632.1981.tb15457.x
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  • 4
    Electronic Resource
    Electronic Resource
    ADH ACTION: EVIDENCE FOR A MEMBRANE SHUTTLE MECHANISM (1981)
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 372 (1981), S. 0 
    Details
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1749-6632.1981.tb15464.x
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  • 5
    Electronic Resource
    Electronic Resource
    Apical and basolateral membrane ionic channels in rabbit urinary bladder epithelium (1985)
    Springer
    Pflügers Archiv 405 (1985), S. S83 
    Details
    ISSN: 1432-2013
    Keywords: Urinary bladder ; Single Na+, K+ anion channels ; Channel turnover ; Channel density
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract This paper reviews the properties and regulation of single amiloride-sensitive Na+ channels in the apical membrane, and Cl− and K+ channels in the basolateral membrane of rabbit urinary bladder. According to fluctuation analysis, there is an average of one amiloride-sensitive Na+ channel for every 40 μm2 of apical membrane. Each Na+ channel passes 0.7 pA of current under normal, short-circuit conditions. Apical channels are hydrolysed by the endogenous enzyme urokinase, which is released into the urine by the kidney. After exposure to urokinase, the Na+ channel loses its amiloride sensitivity, and eventually becomes unstable in the membrane. The selectivity and kinetic properties of single anion and K+ channels in the basolateral membrane were also studied using the patch clamp technique. The properties of these channels are discussed in terms of the regulation of transepithelial Na+ transport.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00581785
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  • 6
    Electronic Resource
    Electronic Resource
    Effects of anions on cellular volume and transepithelial Na+ transport across toad urinary bladder (1985)
    Springer
    The journal of membrane biology 83 (1985), S. 119-137 
    Details
    ISSN: 1432-1424
    Keywords: cell volume ; anions ; Na+ transport ; basolateral K+ conductance ; urinary bladder ; Na+ pump
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary The effects of complete substitution of gluconate for mucosal and/or serosal medium Cl− on transepithelial Na+ transport have been studied using toad urinary bladder. With mucosal gluconate, transepithelial potential difference (V T) decreased rapidly, transepithelial resistance (R T) increased, and calculated short-circuit current (I sc) decreased. CalculatedE Na was unaffected, indicating that the inhibition of Na+ transport was a consequence of a decreased apical membrane Na+ conductance. This conclusion was supported by the finding that a higher amiloride concentration was required to inhibit the residual transport. With serosal gluconateV T decreased,R T increased andI sc fell to a new steady-state value following an initial and variable transient increase in transport. Epithelial cells were shrunken markedly as judged histologically. CalculatedE Na fell substantially (from 130 to 68 mV on average). Ba2+ (3mm) reduced calculatedE Na in Cl− Ringer's but not in gluconate Ringer's. With replacement of serosal Cl− by acetate, transepithelial transport was stimulated, the decrease in cellular volume was prevented andE Na did not fall. Replacement of serosal isosmotic Cl− medium by a hypo-osmotic gluconate medium (one-half normal) also prevented cell shrinkage and did not result in inhibition of Na+ transport. Thus the inhibition of Na+ transport can be correlated with changes in cell volume rather than with the change in Cl− per se. Nystatin virtually abolished the resistance of the apical plasma membrane as judged by measurement of tissue capacitance. With K+ gluconate mucosa, Na+ gluconate serosa, calculated basolateral membrane resistance was much greater, estimated basolateral emf was much lower, and the Na+/K+ basolateral permeability ratio was much higher than with acetate media. It is concluded the decrease in cellular volume associated with substitution of serosal gluconate for Cl− results in a loss of highly specific Ba2+-sensitive K+ conductance channels from the basolateral plasma membrane. It is possible that the number of Na+ pump sites in this membrane is also decreased.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01868744
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  • 7
    Electronic Resource
    Electronic Resource
    Apical membrane area of rabbit urinary bladder increases by fusion of intracellular vesicles: An electrophysiological study (1984)
    Springer
    The journal of membrane biology 82 (1984), S. 123-136 
    Details
    ISSN: 1432-1424
    Keywords: vesicle fusion ; Na+ transport ; aldosterone ; mammalian urinary bladder ; cytoskeleton ; channel degradation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary 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) dit 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01868937
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  • 8
    Electronic Resource
    Electronic Resource
    Urinary proteases degrade epithelial sodium channels (1991)
    Springer
    The journal of membrane biology 122 (1991), S. 77-88 
    Details
    ISSN: 1432-1424
    Keywords: epithelial transport ; sodium channels ; proteases ; channel hydrolysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary The mammalian urinary bladder epithelium accommodates volume changes by the insertion and withdrawal of cytoplasmic vesicles. Both apical membrane (which is entirely composed of fused vesicles) and the cytoplasmic vesicles contain three types of ionic conductances, one amiloride sensitive, an-other a cation-selective conductance and the third a cation conductance which seems to partition between the apical membrane and the mucosal solution. The transport properties of the apical membrane (which has been exposed to urine in vivo) differ from the cytoplasmic vesicles by possessing a lower density of amiloride-sensitive channels and a variable level of leak conductance. It was previously shown that glandular kallikrein was able to hydrolyze epithelial sodium channels into the leak conductance and that this leak conductance was further degraded into a channel which partitioned between the apical membrane and the mucosal solution. This report investigates whether kallikrein is the only urinary constituent capable of altering the apical membrane ionic permeability or whether other proteases or ionic conditions also irreversible modify apical membrane permeability. Alterations of mucosal pH, urea concentrations, calcium concentrations or osmolarity did not irreversible affect the apical membrane ionic conductances. However, urokinase and plasmin (both serine proteases found in mammalian urine) were found to cause an irreversible loss of amiloride-sensitive current, a variable change in the leak current as well as the appearance of a third conductance which was unstable in the apical membrane and appears to partition between the apical membrane and the mucosal solution. Amiloride protects the amiloride-sensitive conductance from hydrolysis but does not protect the leak pathway. Neither channel is protected by sodium. Fluctuation analysis demonstrated that the loss of amiloride-sensitive current was due to a decrease in the sodium-channel density and not a change in the single-channel current. Assuming a simple model of sequential degradation, estimates of single-channel currents and conductances for both the leak channel and unstable leak channel are determined.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01872741
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  • 9
    Electronic Resource
    Electronic Resource
    Effect of protamine sulfate on the permeability properties of the mammalian urinary bladder (1993)
    Springer
    The journal of membrane biology 133 (1993), S. 227-242 
    Details
    ISSN: 1432-1424
    Keywords: epithelial permeability ; protamine ; polycations ; voltage sensitive conductance ; protein binding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary Protamine sulfate (PS, an arginine-rich protein of molecular weight 5,000) has been reported to affect the ionic permeability of gallbladder epithelium, the permeability of cultured epithelial cells to mannitol, and the permeability of endothelial cell layers to albumin. Although the effect of PS has been widely investigated, the mechanism of its action on membrane permeability is presently unknown. The effect of PS on the rabbit urinary bladder epithelium was studied using both transepithelial and intracellular microelectrode techniques in conjunction with equivalent circuit analysis. The addition of 100 μg/ml of PS to a NaCl-containing mucosal solution caused (over a 40-min period) a large increase in the transepithelial conductance (G t )and a transient hyperpolarization of the transepithelial voltage (V t )followed by a depolarization of V t .This secondary depolarization of V t was not present if the mucosal solution was a KCl or a K-gluconate Ringer. The PS-induced increase in G, was due to an increase in the apical membrane permeability to both cations (Na2+ or K2+) and anions (Cl− or gluconate). Further studies revealed the following features of the PS-induced conductance. (i) Trypsin inhibits the PS effect; however, this was due to PS hydrolysis by trypsin and not a membrane effect. (ii) Mucosal PS partially inhibited the PS-induced apical membrane conductance. (iii) The ability of PS to increase the membrane conductance was enhanced when the apical membrane potential was cell interior negative. (iv) The rate of conductance change (at any given membrane potential) was a saturating function of the PS concentration. This finding suggests that PS must interact with a membrane binding site before it can induce a change in the membrane conductance. (v) Lanthanum inhibited the PS-dependent conductance by two different mechanisms. One was as a reversible blocker of the PS-induced conductance. The other was by inhibiting the interaction between PS and a membrane binding site. A kinetic model is developed to describe the steps involved in the increase in membrane conductance.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00232022
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  • 10
    Electronic Resource
    Electronic Resource
    Characterization of a partially degraded Na+ channel from urinary tract epithelium (1988)
    Springer
    The journal of membrane biology 101 (1988), S. 49-56 
    Details
    ISSN: 1432-1424
    Keywords: epithelial Na+ channel ; cation channel ; lipid bilayers ; channel degradation ; channel partitioning ; channel kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary The mammalian urinary bladder contains in its apical membrane and cytoplasmic vesicles, a cation-selective channel or activating fragment which seems to partition between the apical membrane and the luminal (or vesicular space). To determine whether it is an activating fragment or whole channel, we first demonstrate that solution known to contain this moiety can be concentrated and when added back to the bladder causes a conductance increase, with a percent recovery of 139±25%. Next, we show that using tip-dip bilayer techniques (at 21°C) and a patch-clamp recorder, the addition of concentrated solution resulted in the appearance of discrete current shots, consistent with the incorporation of a channel (as opposed to an activating fragment) into the bilayer. The residency time of the channel in the bilayer was best described by the sum of two exponentials, suggesting that the appearance of the channel involves an association of the channel with the membrane before insertion. The channel is cation selective and more conductive to K+ than Na+ (by a factor of 1.6). It has a linearI–V relationship, but a singlechannel conductance that saturates as KCl concentration is raised. This saturation is best described by the Michaelis-Menten equation with aK m of 160mm KCl and aG max of 20 pS. The kinetics of the channel are complex, showing at least two open and two closed states. Since the characteristics of this channel are similar to a channel produced by the degradation of amiloride-sensitive Na+ channels by the proteolytic enzyme kallikrein (which is released by the cortical collecting duct of the kidney), we suggest that this channel then is not synthesized by the cell but is rather a degraded form of the epithelial Na+ channel.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01872819
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