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  • 1
    Electronic Resource
    Electronic Resource
    Clearance of Chlamydia trachomatis– induced polyserositis in SCID mice requires both CD4+ and CD8+ cells (1998)
    Springer
    Medical microbiology and immunology 187 (1998), S. 71-78 
    Details
    ISSN: 1432-1831
    Keywords: Key wordsChlamydia trachomatis ; SCID mice ; Polyserositis ; T cells
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract To characterize the role of specific lymphocyte subsets in Chlamydia trachomatis infection, we established a murine model using the mouse pneumonitis agent (MoPn) of C. trachomatis and C.B-17 scid/scid (SCID) mice which lack functional B and T cells. After intraperitoneal inoculation with the bacteria, SCID mice developed polyserositis with pleuritis, pericarditis, and perihepatitis. Within 8 weeks post infection, SCID mice succumbed to the disease, whereas immunocompetent congenic C.B-17+/+ mice resolved the infection. Adoptive transfer of immune spleen cells into MoPn-infected SCID mice resulted in a complete elimination of the agent and prevention of polyserositis as measured by quantitative chlamydial culture, direct immunofluorescence and histopathological analysis. Selective reconstitution of MoPn-infected SCID mice with immune B lymphocytes, CD4+ T cells or CD8+ T cells alone did not influence the chlamydial load in the lung and liver of infected SCID animals, resulting in a polyserositis as observed in untreated MoPn-infected SCID mice. However, co-transfer of both CD4+ T cells and CD8+ T cells led to a significant reduction of chlamydiae in quantitative organ culture coupled with unremarkable histopathology. These data confirm that T cell-mediated immune responses are essential for immune protection in chlamydial infection, although total eradication of the agent could not be achieved. Further experiments are needed to stress the importance of a concerted action of B and T lymphocytes, as indicated by the complete protective efficacy of transferred splenocytes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004300050076
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  • 2
    Electronic Resource
    Electronic Resource
    Effect of aldosterone on active and passive conductance andE Na in the toad bladder (1973)
    Springer
    The journal of membrane biology 13 (1973), S. 1-18 
    Details
    ISSN: 1432-1424
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary It has been demonstrated previously that aldosterone increases the electrical conductance of the toad bladder in association with the stimulation of active sodium transport. In the present study the concurrent measurement of electrical quantities and ion tracer flux distinguishes effects on active and passive pathways. Lack of an effect on passive Na+ or Cl− tracer flux in hemibladders preselected to eliminate large artefactual leaks indicates that aldosterone has no influence on physiological passive conductance. Thus, the enhancement of electrical conductance is entirely attributable to the active pathway. The magnitude of the increase in the active conductance was estimated. The data permitted also the comparison of effects on the flux ratio of Na+ at short circuit (f 0) and the electrical potential difference adequate to abolish active sodium transport (E Na). Even in membranes with minimal leakage the flux ratio does not reliably reflectE Na. Aldosterone increased meanf 0 from 11 to 22, but did not affectE Na.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01868217
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  • 3
    Electronic Resource
    Electronic Resource
    Comments on: Sodium fluxes through the active transport pathway in toad bladder (1975)
    Springer
    The journal of membrane biology 24 (1975), S. 401-406 
    Details
    ISSN: 1432-1424
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01868634
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  • 4
    Electronic Resource
    Electronic Resource
    Effects of 2-deoxy-d-glucose, amiloride, vasopressin, and ouabain on active conductance andE Na in the toad bladder (1976)
    Springer
    The journal of membrane biology 28 (1976), S. 121-142 
    Details
    ISSN: 1432-1424
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary The effects of various agents on active sodium transport were studied in the toad bladder in terms of the equivalent circuit comprising an active conductanceK a, an electromotive forceE Na, and a parallel passive conductanceK p. For agents which affectK a, but notE Na orK p, the inverse slope of the plot of total conductance κ against short-circuit currentI 0 evaluatesE Na, and the intercept representsK p. Studies employing 5×10−7 m amiloride to depressK a indicate a changingE Na, invalidating the use of the slope technique with this agent. An alternative suitable technique employs 10−5 m amiloride, which reducesI 0 reversibly to near zero without effect onK p. Despite curvilinearity of the κ-I0 plot under these conditions,K p may therefore be estimated fairly precisely from the residual conductance. It then becomes possible to follow the dynamic behavior ofK a andE Na (in the absence of 10−5 m amiloride) by frequent measurements of κ andI 0, utilizing the relationshipsK a=K-K p, andK Na=I O/(K-K p). 2-deoxy-d-glucose (7.5×10−3 m) depressedK a without affectingE Na. Amiloride (5×10−7 m) depressedK a and enhancedE Na. Vasopressin (100 mU/ml) enhancedK a markedly and depressedE Na slightly. Ouabain (10−4 m) depressed bothK a andE Na. All of the above effects were noted promptly;K p was unaffected. The “electromotive force of Na transport”E Na appears not to be a pure energetic parameter, but to reflect kinetic factors as well, in accordance with thermodynamic considerations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01869693
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  • 5
    Electronic Resource
    Electronic Resource
    Basolateral membrane potential and conductance in frog skin exposed to high serosal potassium (1986)
    Springer
    The journal of membrane biology 90 (1986), S. 89-96 
    Details
    ISSN: 1432-1424
    Keywords: frog skin ; membrane potential ; voltage clamp ; K+ depolarization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary In studies of apical membrane current-voltage relationships, in order to avoid laborious intracellular microelectrode techniques, tight epithelia are commonly exposed to high serosal K concentrations. This approach depends on the assumptions that high serosal K reduces the basolateral membrane resistance and potential to insignificantly low levels, so that transepithelial values can be attributed to the apical membrane. We have here examined the validity of these assumptions in frog skins (Rana pipiens pipiens). The skins were equilibrated in NaCl Ringer's solutions, with transepithelial voltageV t clamped (except for brief perturbations ΔV t) at zero. The skins were impaled from the outer surface with 1.5m KCl-filled microelectrodes (R el〉30 MΩ). The transepithelial (short-circuit) currentl i and conductanceg t=−ΔI t/ΔV t, the outer membrane voltageV o (apical reference) and voltage-divider ratio (F o=ΔV o/ΔV t), and the microelectrode resistanceR el were recorded continuously. Intermittent brief apical exposure to 20 μm amiloride permitted estimation of cellular (c) and paracellular (p) currents and conductances. The basolateral (inner) membrane conductance was estimated by two independent means: either from values ofg i andF o before and after amiloride or as the ratio of changes (−ΔI c/ΔV i) induced by amiloride. On serosal substitution of Na by K, within about 10 min,I c declined andg t increased markedly, mainly as a consequence of increase ing p. The basolateral membrane voltage (V i(=−V o) was depolarized from 75±4 to 2±1 mV [mean±sem (n=6)], and was partially repolarized following amiloride to 5±2 mV. The basolateral conductance increased in high serosal K, as estimated by both methods. Essentially complete depolarization of the basolateral membrane and increase in its conductance in response to high [K] were obtained also when the main serosal anion was SO4 or NO3 instead of Cl. On clampingV t over the range 0 to +125 mV in K2SO4-depolarized skins, the quasi-steady-stateV o V t relationship was linear, with a mean slope of 0.88±0.03. The above results demonstrate that, in a variety of conditions, exposure to high serosal K results in essentially complete depolarization of the basolateral membrane and a large increase in its conductance.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01869688
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  • 6
    Electronic Resource
    Electronic Resource
    Voltage dependence of cellular current and conductances in frog skin (1988)
    Springer
    The journal of membrane biology 106 (1988), S. 13-28 
    Details
    ISSN: 1432-1424
    Keywords: cell potential ; amiloride ; sodium transport ; reversal potential
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary Knowledge of the voltage dependencies of apical and basolateral conductances is important in determining the factors that regulate transcellular transport. To gain this knowledge it is necessary to distinguish between cellular and paracellular currents and conductances. This is generally done by sequentially measuring transepithelial current/voltage (I t /V t ) and conductance/voltage (g t /V t ) relationships before and after the abolition of cellular sodium transport with amiloride. Often, however, there are variable time-dependent and voltage-dependent responses to voltage perturbation both in the absence and presence of amiloride, pointing to effects on the paracellular pathway. We have here investigated these phenomena systematically and found that the difficulties were significantly lessened by the use of an intermittent technique, measuringI t andg t before and after brief (〈10 sec) exposure to amiloride at each setting ofV t .I/V relationships were characterized by these means in frog skins (Rana pipiens, Northern variety, andRana temporaria). Cellular current,I c , decreased with hyperpolarization (larger serosa positive clamps) ofV t . DerivedI c /V t relationships betweenV t =0 and 175 mV (serosa positive) were slightly concave upwards. Because values of cell conductance,g c , remained finite, it was possible to demonstrate reversal ofI c . Values of the reversal potentialV' averaged 156±14 (sd,n=18) mV. Simultaneous microelectrode measurements permitted also the calculation of apical and basolateral conductances,g a andg b . The apical conductance decreased monotonically with increasing positivity ofV t (andV a ). In contrast, in the range in which the basolateral conductance could be evaluated adequately (V t 〈125 mV),g b increased with more positive values ofV t (andV b ). That is, there was an inverse relation betweeng b and cellular current at the quasi-steady state, 10–30 sec after the transepithelial voltage step.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01871763
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  • 7
    Electronic Resource
    Electronic Resource
    Influence of membrane heterogeneity on kinetics of nonelectrolyte tracer flows (1976)
    Springer
    The journal of membrane biology 29 (1976), S. 255-264 
    Details
    ISSN: 1432-1424
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary In a composite membrane with heterogeneous channels, prevention of net volume flow with hydrostatic pressure differences and/or impermeant osmotic solutes may induce positive isotope interaction (coupling of isotope flows) consequent to circulation of volume flow. The permeability coefficient for net flow will then exceed the tracer permeability coefficient. A permeant osmotic solute will induce either positive or negative isotope interaction, according to whether membrane heterogeneity is more marked for the test solute or the osmotic solute, respectively. Thus membrane heterogeneity may account for phenomena commonly attributed to “single file diffusion” or “exchange diffusion”. For sufficiently small flows the general flux ratio relationship for homogeneous membranes will continue to apply.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01868965
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  • 8
    Electronic Resource
    Electronic Resource
    Thermodynamic analysis of active sodium transport and oxidative metabolism in toad urinary bladder (1977)
    Springer
    The journal of membrane biology 31 (1977), S. 19-29 
    Details
    ISSN: 1432-1424
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary Measurements of electrical current and oxygen consumption were carried out concurrently under voltage clamp conditions in 11 toad hemibladders. Inhibition of active transport with amiloride then permitted evaluation of the passive conductance and the rate of basal oxygen consumptionJ r b , allowing the simultaneous determination of the rates of active sodium transportJ Na a and suprabasal, oxygen consumptionJ r sb .J Na a andJ r sb were linear functions of the electrical potential difference over a range of ±80 mV. This allowed the comprehensive application of a linear nonequilibrium thermodynamic formalism, leading to the evaluation of the affinityA (negative free energy) of the metabolic reaction driving transport, all phenomenological coefficients, and the degree of couplingq relating transport to metabolism. Values ofA determined by two techniques wereA 1=56.0±5.8 andA 2=58.2±6.5 kcal per mole. Values ofq determined by two techniques agreed well and were less than 1, indicating incompleteness of coupling, and hence lack of fixed stoichiometry between Na transport and O2 consumption. The affinity and the electromotive force of sodium transportE Na are not closely correlated, reflecting the fact thatE Na comprises both kinetic and energetic factors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01869397
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  • 9
    Electronic Resource
    Electronic Resource
    Influence of serosal Cl on transport properties and cation activities in frog skin (1988)
    Springer
    The journal of membrane biology 106 (1988), S. 107-118 
    Details
    ISSN: 1432-1424
    Keywords: frog skin ; microelectrodes ; K activity ; Na activity ; membrane conductance ; chloride
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary The effects of serosal substitution of isosmotic Na2SO4-Ringer solution for NaCl-Ringer solution were studied in the short-circuited frog skin (Rana pipiens, Northern variety). Despite prompt changes of transepithelial measurements, initial cellular effects were slight. After 30 to 45 min, however, the transcellular current had decreased and the cell electrical potential had depolarized, in association with decrease of the apical membrane fractional resistance and basolateral membrane conductance. Apical membrane slope conductance was unaffected. Similar effects were obtained with isolated epithelia. With the use of gluconate or NO3 in place of Cl, the effects on cellular current and conductance were minimal or insignificant, despite changes of the cell potential, fractional resistance, and basolateral conductance similar to those seen with sulfate. Following prolonged exposure to serosal SO4-Ringer, the extent of depolarization induced by raising the serosal K concentration decreased, indicating diminution of basolateral K conductance and the existence of other basolateral conductances. Equilibration in serosal gluconate-Ringer enhanced polarization on serosal restoration of Cl or removal of Na, again indicating a time-dependent change in the basolateral conductance pattern. Depolarization on removal of serosal Cl was not attributable to inhibition of the pump. Nor was it the result of decrease of the K equilibrium potentialE K: exposure to serosal SO4-Ringer decreased cell K activitya K c from 104±6 to 58±4mm (n=5), butE K was reduced only slightly; exposure to serosal gluconate increaseda K c andE K. Serosal sulfate lowered the cell Na activitya Na c , but the electrochemical potential difference for Na across the apical surface was unaffected. The concurrent decrease of botha K c anda Na c following serosal substitution of SO4 for Cl raises questions concerning mechanisms of osmoregulation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01871392
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  • 10
    Electronic Resource
    Electronic Resource
    Tracer flow, permeability, and partial conductance (1975)
    Springer
    The journal of membrane biology 20 (1975), S. 341-346 
    Details
    ISSN: 1432-1424
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary It is often not possible to evaluate a permeability coefficient for net flowP from the small flows produced by physiological gradients of concentration or electrical potential. The common use of a tracer permeability coefficientP x for this purpose, under the assumption thatP x =P, requires that the species be transported passively, and that there be no significant coupling between its flow and that of other chemical species, and between the flows of its tracer and abundant isotopes (isotope interaction). These conditions are often not satisfied. However, for passive transport in the absence of coupling of flows of different chemical species the measurement of tracer flow at two values of electrical potential difference evaluates (P x /P) and thusP. In the presence of coupling of flows of different chemical species, although these measurements no longer evaluateP, they evaluate the partial conductanceG. A graphical method of evaluating (P x /P),P andG is presented.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01870642
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