Library

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Does tissue ATP content limit active sodium transport across intestinal epithelia in vitro? (1982)
    Springer
    Pflügers Archiv 395 (1982), S. 257-259 
    Details
    ISSN: 1432-2013
    Keywords: Intestinal epithelium ; sodium absorption ; active transport ; ATP ; adenosine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The ATP content of isolated epithelia of rabbit descending colon, incubated in oxygenated Ringer solution containing glucose, is increased by addition of 1 mM adenosine from 10.9±1.4 to 22.2±2.3 pmoles/mg, but the transport rate of the Na pump is not altered. It is therefore concluded that epithelial ATP synthesis is not rate-limiting for Na transport in this tissue under conditions of in vitro aerobic incubation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00584820
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Sodium pump quantity and turnover in rabbit descending colon at different rates of sodium absorption (1988)
    Springer
    Pflügers Archiv 413 (1988), S. 181-189 
    Details
    ISSN: 1432-2013
    Keywords: Sodium pump ; Na+,K+-ATPase regulation and turnover ; Sodium absorption ; Rabbit colon ; Aldosterone ; Basolateral membrane vesicles of epithelial cells ; Ouabain binding ; Binding kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract 3H-Ouabain binding to isolated epithelia and basolateral membrane vesicles of Na+-transporting epithelial cells of rabbit descending colon was determined to quantify the number of operative Na+-pump sites at different rates of transcellular Na+ transport which was varied over a wide range by chronic dietary Na+ restriction or Na+ loading. Both in intact epithelia and in basolateral membrane vesicles the maximal number of specific ouabain binding sites was higher in preparations from animals transporting Na+ at high rates than in preparations from animals transporting Na+ at low rates. The affinity of ouabain to its binding site and the association and dissociation rate constants were not dependent on the rate of Na+ transport. In intact epithelia the Na+ turnover rate per pump unit was twice as high in tissues with high Na+ transport than in tissues with low Na+ transport. In basolateral membrane vesicles the Na+ turnover rate was considerably higher than in intact epithelia and there was no difference in turnover rate between vesicle preparations obtained from tissues transporting Na+ at high or low rates. Hence, factors within the intact cell appear to control the turnover rate of the Na+-pump.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00582529
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Myocardial glucose uptake and breakdown during adenosine-induced vasodilation (1976)
    Springer
    Pflügers Archiv 365 (1976), S. 197-202 
    Details
    ISSN: 1432-2013
    Keywords: Adenosine ; Isolated perfused heart ; Myocardial glucose uptake ; Glucose metabolism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In isolated K+ (16.2 mM)-arrested cat hearts perfused at constant pressure adenosine infusions (0.8 μmoles · min−1 · 100 g−1 for 10 min) caused an increase in myocardial14C-glucose uptake and release of14CO2+H14CO − 3 and14C-lactate simultaneously with a rise in coronary flow. The ratio of the release of14CO2+H14CO − 3 to that of14C-lactate and the specific activity of lactate in the effluate were not altered. In K+-arrested hearts perfused with constant volume neither glucose uptake nor glucose breakdown were influenced by 0.8 or 100 μmoles · min−1 · 100 g−1 adenosine with 0.1–5 mM glucose in the perfusion medium. It is concluded that adenosine does not affect directly the myocardial glucose carrier system, aerobic or anaerobic glucose breakdown or glycogenolysis, but enhances glucose uptake secondarily by increasing coronary flow. This interpretation is substantiated by the finding that mechanically produced increases in perfusion volume caused similar increases in myocardial glucose uptake as were observed with comparable adenosine-induced coronary flow increments.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01067019
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Endothelin-1 stimulates chloride and potassium secretion in rabbit descending colon (1992)
    Springer
    Pflügers Archiv 421 (1992), S. 163-167 
    Details
    ISSN: 1432-2013
    Keywords: Endothelin ; Intestinal electrolyte transport ; Intestinal epithelium ; Chloride secretion ; Sodium/potassium ATPase ; Prostaglandins
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The vasoactive peptide endothelin-1 (ET-1) which is present in high concentrations in the colon, causes concentration-dependent electrogenic Cl− secretion in rabbit descending colon. This effect is half-maximal at 0.11 μmol/l. Like other secretagogues, ET-1 also stimulates K+ secretion. The secretory effect of ET-1 is associated with increased release of prostaglandin E2 from the serosal surface of the mucosa. ET-1-induced Cl− secretion is completely inhibited by the loop diuretic bumetanide and by indomethacin and quinacrine, inhibitors of prostaglandin synthesis. Neuronal mechanisms do not seem to be involved, as tetrodotoxin did not affect the secretory response to ET-1 significantly. On the other hand, neither the catalytic activity nor the transport function of the Na+/K+-ATPase of rabbit colon epithelium is affected by endothelin-1 (ET-1) in concentrations up to 10 μmol/l. It is concluded that ET-1 causes Cl− and K+ secretion by stimulating phospholipase A2 and release of prostaglandins, whereas Na+ transport is not altered.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00374823
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Absorption and secretion of potassium by rabbit descending colon (1986)
    Springer
    Pflügers Archiv 406 (1986), S. 509-519 
    Details
    ISSN: 1432-2013
    Keywords: Colonic epithelium ; Potassium absorption ; Potassium secretion ; Intestinal electrolyte transport ; Sodium-chloride-potassium cotransport ; Paracellular pathway ; furosemide ; 5′-N-ethylcarboxamide adenosine (NECA)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Measurements of K fluxes under a variety of conditions have provided an internally consistent set of data that demonstrate active absorption and active secretion of K by rabbit descending colon in vitro. The properties of K diffusion across the paracellular pathway are those of a free solution shunt. With Na and Cl present on both sides of short-circuited tissues the two opposing active K transport systems balance each other, so that there is no net K transport. Net K absorption results when the transcellular secretory K flux is inhibited by 1. serosal addition of ouabain, 2. serosal addition of furosemide, or 3. omission of either Na or Cl from the serosal solution. Hence basolateral K uptake appears to be mediated by a furosemide-sensitive Na−Cl−K cotransport system in addition to the Na−K exchange pump. Luminal addition of mersalyl or orthovanadate inhibits active K absorption. The adenosine analogue 5′-N-ethylcarboxamide adenosine and the β-adrenergic agent isoproterenol, added to the serosal solution, cause net K secretion which is inhibitable by furosemide. The secretory K fluxes, both under stimulated and non-stimulated conditions, are abolished by an opposing electrical gradient, suggesting conductive K exit across the apical cell membrane, whereas K absorption appears to be an electroneutral process.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00583375
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Cell Na+ activities and transcellular Na+ absorption by descending colon from normal and Na+-deprived rabbits (1987)
    Springer
    Pflügers Archiv 410 (1987), S. 279-283 
    Details
    ISSN: 1432-2013
    Keywords: Rabbit colon ; Hyperaldosteronism ; Sodium absorption ; Cell sodium activity ; Membrane conductances
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The relation between intracellular Na+ activities, (Na)c, determined employing Na+-selective microelectrodes, and the rates of active Na+ absorption,I Na, by rabbit descending colon was examined whenI Na was varied over a wide range by chronic dietary Na+ deprivation. (Na)c averaged 13 mM and was independent ofI Na over a sixfold range. Further, the ratios of the slope resistance of the apical membrane (r m) to that of the basolateral membrane (r s) (i.e.r m/r s) in low-transporters (control diet) and high-transporters (Na+-deprived) did not differ significantly inspite of the fact that the Na+ conductance of the apical membranes of high-transporters was, on the average, three times greater than that of the low-transporters. These findings, together with the results reported by other laboratories, strongly suggest that the aldosterone-induced increase in the conductance of the apical membrane to Na+ and, in turn, the rate of entry of Na+ into the absorptive cells are followed by parallel increases in the ability of cells to extrude Na+ across the basolateral membrane in the absence of a sustained increase in (Na)c as well as the conductance of that barrier.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00580277
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Rabbit distal colon epithelium: I. Isolation and characterization of basolateral plasma membrane vesicles from surface and crypt cells (1989)
    Springer
    The journal of membrane biology 110 (1989), S. 147-162 
    Details
    ISSN: 1432-1424
    Keywords: rabbit distal colon ; surface and crypt cells ; basolateral membrane ; osmotic water permeability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary A method has been developed for the simultaneous isolation of basolateral plasma membrane vesicles from surface and crypt cells of rabbit distal colon epithelium by sequential use of differential sedimentation, isopycnic centrifugation and Ficoll 400 barrier centrifugation. The protein yield was high (total 0.81 mg/g mucosa) and surface and crypt cell-derived basolateral membrane fractions have been purified 34- and 9-fold with respect to the homogenate. The pattern of marker enzyme enrichments revealed only minor contamination by subcellular organelles. Latency of ouabain-sensitive (Na+, K+)-ATPase activity prior and after trypsin treatment of membranes indicated a vesicle configuration of sealed right side-out: sealed inside-out: leaky of approximately 2∶1∶1. The presence of sealed vesicles was also evident from the osmotic sensitivity of thed-[1-14C] mannitol equilibrium space determined with either fraction. Although considerably different in protein profile, surface and crypt basolateral membranes were similar in cholesterol to phospholipid molar ratio and membrane fluidity as determined by steady-state fluorescence polarization. Stopped-flow light scattering experiments revealed a rather low water permeability of the membranes with a permeability coefficient of 6 μm/sec at 35°C, which is one order of magnitude lower than reported for small intestinal plasma membranes. Both membrane fractions have been shown to effectively generate outward uphill potassium ion gradients, a process that is energized by ATP and inhibited by the membrane-permeant cardiacglycoside digitoxin. These characteristics are consistent with the activity of a (Na+, K+) pump operating in inside-out vesicles.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01869470
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Ion transport by rabbit colon: II. Unidirectional sodium influx and the effects of amphotericin B and amiloride (1978)
    Springer
    The journal of membrane biology 40 (1978), S. 193-211 
    Details
    ISSN: 1432-1424
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary The unidirectional influx of Na from the mucosal solution into the epithelium ofin vitro descending rabbit colon (J me Na ) determined under short-circuit conditions, is comprised of two components: one represents entry of Na into transporting epithelial cells and is abolished by amiloride which also abolishes Na absorption (J net Na ). The other represents diffusional Na entry into paracellular pathways traversing the epithelium. In all instances, exposure of the mucosal surface to amphotericin B increased tissue conductance andJ me Na and elicited K secretion. Tissues showing a spontaneousI sc of approximately 4 μeq/cm2hr did not respond to amphotericin B with increasedI sc andJ net Na . However, in tissues characterized by a lowerI sc under control conditions, amphotericin B increasedI sc andJ net Na to approximately 4μeq/cm2hr. These findings suggest that amphotericin increasesJ net Na and elicits K secretion by disrupting the normal permselectivity of the mucosal membrane. Under these conditions the extrusion of Na from cell-to-serosal solution becomes the rate limiting step in transepithelial Na transport. Finally, a close correlation betweenJ me Na andJ net Na was observed when the rate of Na absorption varied either spontaneously or experimentally with amiloride, suggesting that the backflux of Na from cell-to-mucosal solution is undetectably small.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02002968
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    Interaction between cell sodium and the amiloride-sensitive sodium entry step in rabbit colon (1978)
    Springer
    The journal of membrane biology 39 (1978), S. 233-256 
    Details
    ISSN: 1432-1424
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary Ouabain abolishes the short-circuit current (I sc ) and decreases the transepithelial conductance (G t ) of rabbit colon. In contrast, amphotericin B elicits a maximumI sc and markedly increasesG t . However, inboth instances the amiloride-sensitive Na entry step is completely blocked, presumably due to an increase in cell Na. Conversely, when Na-depleted tissues are suddenly exposed to 140mm Na, the amiloride-sensitiveI sc and the amiloride-sensitive component ofG t ( a G Na ) increase abruptly to their maximum values and the decline to steady-state plateaus with a half time of ∼ 6 min; throughout the decline (I sc/a G Na)=E Na is constant at a value of 95 mV. In the presence of amphotericin B, theI sc abruptly rises to the same maximum but does not decline. These findings indicate that in the presence of 140mm Na the conductance of the amiloride-sensitive Na entry step can vary from a maximum value of approximately 1.6 mmhos/cm2 when cell Na is depleted, to zero when cell Na is abnormally elevated (e.g., in the presence of ouabain or amphotericin B). Our findings are consistent with a system in which the pathway responsible for transcellular Na transport parallels another cellular compartment with which it communicates. The Na capacity of the active transport pathway appears to be very small so that this compartment fills rapidly after exposure of Na-depleted cells to 140mm Na, and active transepithelial Na transport is initiated and reaches steady-state levels quickly. The Na capacity of the second compartment is much larger; the Na content of this compartment appears to be responsible for the negative feedback effect on the permeability of the amiloride-sensitive entry step.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01870333
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    Relation between intracellular sodium and active sodium transport in rabbit colon: Current-voltage relations of the apical sodium entry mechanism in the presence of varying luminal sodium concentrations (1983)
    Springer
    The journal of membrane biology 76 (1983), S. 299-309 
    Details
    ISSN: 1432-1424
    Keywords: rabbit descending colon ; electrophysiology ; current-voltage relations ; sodium transport ; cell Na activity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary The current-voltage relations of the amiloride-sensitive Na entry pathway across the apical membrane of rabbit descending colon, exposed to a high K serosal solution, were determined in the presence of varying mucosal Na activities, (Na) m , ranging from 6.2 to 99.4mm. These relations could be closely fit to the “constant field” flux equation yielding estimates of the permeability of the apical membrane to Na,P Na m , and the intracellular Na activity, (Na) c . The following empirical relations emerged: (i) (Na) c increased hyperbolically with increasing (Na) m ; (ii)P Na m decreased hyperbolically with increasing (Na) m and linearly with increasing (Na) c ; (iii) spontaneous variations in Na entry rate at constant (Na) m could be attributed entirely to parallel, spontaneous variations inP Na m ; (iv) the rate of Na entry increased hyperbolically with increasing (Na) m obeying simple Michaelis-Menten kinetics; (v) the relation between (Na) c and “pump rate,” however, was sharply sigmoidal and could be fit by the Hill equation assuming strong cooperative interactions between Na and multiple sites on the pump; the Hill coefficient was 2–3 and the value of (Na) c at which the pump-rate is half-maximal was 24mm. The results provide an internally consistent set of relations among Na entry across the apical membrane, the intracellular Na activity and basolateral pump rate that is also consistent with data previously reported for this and other Na-absorbing epithelia.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01870372
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...