scholarly journals K Fluxes in Frog Skin

1965 ◽  
Vol 48 (6) ◽  
pp. 1011-1033 ◽  
Author(s):  
Peter F. Curran ◽  
Marcelino Cereijido
Keyword(s):  
Epithelial Cells ◽  
Connective Tissue ◽  
Active Transport ◽  
Time Constant ◽  
Frog Skin ◽  
Bathing Solution ◽  
Na Transport ◽  
K Uptake ◽  
Low Concentrations ◽  
K Concentration

A method has been developed for measuring K influx into the epithelial cells of frog skin from the inside solution. Diffusion delay in the connective tissue has been taken into account. Ninety-four per cent of skin K was found to exchange with K42 in the inside solution with a single time constant. K influx showed saturation with increasing K concentration, was not altered by imposing a potential difference of ±200 mv across the skin, and was inhibited by dinitrophenol, fluoroacetate, and ouabain. Relatively low concentrations of dinitrophenol (5 x 10-5 M) and fluoroacetate (10-10 M) had no effect on k influx but caused a 40 per cent decrease in net Na flux. There was no correlation between the rate of K uptake at the "inner barrier" and the rate of net Na transport. Reduction of net Na transport by lowering Na concentration in the outside solution caused little change in K uptake. These observations indicate that there is not a significant Na-K exchange involved in active transport of Na across the skin. K influx was found, however, to require Na in the inside bathing solution.

scholarly journals Isolated Epithelial Cells of the Toad Bladder

1968 ◽  
Vol 51 (6) ◽  
pp. 770-784 ◽  
Author(s):  
J. T. Gatzy ◽  
W. O. Berndt
Keyword(s):  
Epithelial Cells ◽  
Connective Tissue ◽  
Divalent Cation ◽  
Toad Bladder ◽  
Trypsin Treatment ◽  
Na Transport ◽  
Isolated Cells ◽  
General Increase ◽  
High Sucrose ◽  
Isolated Cell

Epithelial cells of the toad bladder were disaggregated with EDTA, trypsin, hyaluronidase, or collagenase and were then scraped free of the underlying connective tissue. In most experiments EDTA was complexed with a divalent cation before the tissue was scraped. QOO2, sucrose and inulin spaces, and electrolytes of the isolated cells were measured. Cells disaggregated by collagenase or hyaluronidase consumed O2 at a rate of 4 µl hr-1 dry wt-1. QOO2 was increased 50% by ADH (100 U/liter) or by cyclic 3',5'-AMP (10 mM/liter). Na+-free Ringer's depressed the QOO2 by 40%. The QOO2 of cells prepared by trypsin treatment or by two EDTA methods was depressed by Na+-free Ringer's but was stimulated relatively little by ADH. Two other EDTA protocols produced cells that did not respond to Na+ lack or ADH. The intracellular Na+ and K+ concentrations of collagenase-disaggregated cells were 32 and 117 mEq/kg cell H2O, respectively. Cation concentrations of hyaluronidase cells were similar, but cells that did not respond to ADH had higher intracellular Na+ concentrations. Cells unresponsive to ADH and Na+ lack had high sucrose spaces and low transcellular membrane gradients of Na+, K+, and Cl-. The results suggest that trypsin and EDTA disaggregation damage the active Na+ transport system of the isolated cell. Certain EDTA techniques may also produce a general increase in permeability. Collagenase and hyaluronidase cells appear to function normally.

scholarly journals The Effect of Ca and Antidiuretic Hormone on Na Transport across Frog Skin

1963 ◽  
Vol 46 (5) ◽  
pp. 1011-1027 ◽  
Author(s):  
Peter F. Curran ◽  
Francisco C. Herrera ◽  
William J. Flanigan
Keyword(s):  
Outer Membrane ◽  
Antidiuretic Hormone ◽  
Active Transport ◽  
Direct Effect ◽  
Transport System ◽  
Frog Skin ◽  
Na Transport ◽  
Diuretic Hormone ◽  
Na Permeability ◽  
Active Transport System

A method has been developed for determining unidirectional Na fluxes across the two faces of the transporting cells in the frog skin. The method has been used to investigate the location of the sites at which Ca and anti-diuretic hormone act to alter the rate of active Na transport across the skin. The results have indicated that the primary effect of both agents is on the Na permeability of the outward facing membrane of the cells. Ca decreases and the hormone increases permeability of this barrier. Neither agent appears to have a direct effect on the active transport system itself assuming that it is located at the inner membrane of the cells. The rate of active Na transport is altered as a result of changes in the size of the Na pool in the cells which occur because of changes in the rate of Na entry through the outer membrane. Thus, the results indicate that the Na permeability of the outer membrane plays an important role in controlling the rate of net active Na transport across the skin.

Evidence for active Na+ transport by cultured monolayers of pulmonary alveolar epithelial cells

1983 ◽  
Vol 245 (1) ◽  
pp. C78-C83 ◽  
Author(s):  
B. E. Goodman ◽  
R. S. Fleischer ◽  
E. D. Crandall
Keyword(s):  
Epithelial Cells ◽  
Active Transport ◽  
Alveolar Epithelial Cells ◽  
Metabolic Inhibitors ◽  
Normal Lung ◽  
Type Ii ◽  
Na Transport ◽  
Alveolar Epithelial ◽  
Cl Transport ◽  
Transport Inhibitors

Primary cultured type II alveolar epithelial cells grown to confluence on nonporous surfaces form many small fluid-filled hemicysts or domes. These domes are generally thought to result from active transport of solutes from the medium above the cell monolayer to the substratum, with water following passively. We have investigated the characteristics of active transport by primary cultured monolayers of type II alveolar epithelial cells from rat lungs. Changes in dome density were measured after exposure to metabolic inhibitors, Na+ or Cl- transport inhibitors, and low-Na+ or low-Cl- culture media. Metabolic and Na+ transport inhibitors, and low-Na+ medium, lead to disappearance of domes, whereas Cl- transport inhibitors and low-Cl- medium seem to have no effect on dome density. These results suggest the presence of a Na+-dependent active transepithelial transport process across the monolayer, which is responsible for the formation of domes. This finding implies that absorption of fluid by mammalian alveolar epithelium in vivo may be important in the maintenance of normal lung fluid balance.

Dependence of intracellular Na+ concentration on apical and basolateral membrane Na+ influx in frog skin

1985 ◽  
Vol 249 (5) ◽  
pp. F662-F671
Author(s):  
J. S. Stoddard ◽  
S. I. Helman
Keyword(s):  
Epithelial Cells ◽  
Frog Skin ◽  
Apical Membrane ◽  
Basolateral Membrane ◽  
Na Transport ◽  
Maximal Inhibition ◽  
Basolateral Membranes ◽  
Isotopic Method ◽  
Rate Of Increase ◽  
Kinetics Of

An isotopic method was developed to measure the intracellular Na+ content of the transepithelial Na+ transport pool of frog skin. Isolated epithelia (no corium) were labeled with 24Na either asymmetrically, from apical (Aa) or basolateral (Ab) solutions, or symmetrically (Aab). Transport pool Na+ could be identified from the kinetics of washout of 24Na carried out in the presence of 1 mM ouabain, 100 microM amiloride, and 1 mM furosemide that served to trap cold Na+ and 24Na within the transport pool. In control epithelia, Aab averaged 64.1 neq/cm2 (13.9 mM), and maximal inhibition of apical membrane Na+ entry with 100 microM amiloride caused Aab to decrease to 24.3 neq/cm2 (5.3 mM). Ouabain caused Aab to increase markedly to 303 neq/cm2 in 30 min, whereas amiloride inhibition of apical membrane Na+ entry reduced markedly the rate of increase of Aab caused by ouabain (7.3 neq X cm-2 X min-1 in control and 1.7 neq X cm-2 X min-1 in the presence of amiloride). These data, in part, confirmed the existence of an important basolateral membrane permeability to Na+ that was measured in separate studies of the bidirectional 24Na fluxes at the basolateral membranes of the cells. Both sets of data were supportive of the idea that a significant Na+ recycling exists at the basolateral membranes of the cells that contributes to the Na+ load on the pump and Na+ recycling participates in the regulation of the Na+ concentration of the Na+ transport pool of these epithelial cells.

Chloride transport across isolated skin of Rana pipiens

1975 ◽  
Vol 229 (3) ◽  
pp. 869-876 ◽  
Author(s):  
RH Alvarado ◽  
TH Dietz ◽  
TL Mullen
Keyword(s):  
Active Transport ◽  
Frog Skin ◽  
Rana Pipiens ◽  
Chloride Transport ◽  
Iodoacetic Acid ◽  
Temperature Sensitive ◽  
Na Transport ◽  
Exchange Diffusion ◽  
Paracellular Pathways ◽  
Unidirectional Fluxes

The influx of Cl- across isolated frog skin bathed on the outside by 0.8 mM NaCl is about 100 nmol cm-2 h-1, which is approximately twice the Cl- influx in intact animals. The influx consists of diffusion (1%), exchange diffusion (38%), and active transport (60%). About 80% of the influx is independent of Na+ in the outer bath and is also independent of concomitant inward movement of cations. Chloride is exchanged for anions, probably HCO-3. The Cl- transport system is saturable; Vmax is about 200 nmol cm-2 h-1, and Ks is about 0.7 mM Cl-. High external concentrations of NaCl increase unidirectional fluxes of Cl- and urea, indicating a change in paracellular pathways. Active transport of Cl- is temperature sensitive (Q10 equals 2.68) and is inhibited by cyanide, dinitrophenol, iodoacetic acid, iodide, thiocyanate, and acetazolamide. The Na-independent component of JClin was unaffected by amiloride, ouabain, or eserine, all of which inhibit Na+ transport.

scholarly journals Cation transport in Escherichia coli. VIII. Potassium transport mutants.

1976 ◽  
Vol 67 (3) ◽  
pp. 325-341 ◽  
Author(s):  
D B Rhoads ◽  
F B Waters ◽  
W Epstein
Keyword(s):  
Escherichia Coli ◽  
Transport Systems ◽  
K Uptake ◽  
Low Concentrations ◽  
Transport Mutants ◽  
High Concentrations ◽  
K Concentration ◽  
Independent Path ◽  
Kinetics Of Uptake ◽  
K 12

Analysis of K transport mutants indicates the existence of four separate K uptake systems in Escherichia coli K-12. A high affinity system called Kdp has a Km of 2 muM, and Vmax at 37 degrees C of 150 mumol/g min. This system is repressed by growth in high concentrations of K. Two constitutive systems, TrkA and TrkD, have Km's of 1.5 and 0.5 mM and Vmax's of 550 and 40 at 37 and 30 degrees C, respectively. Mutants lacking all three of these saturable systems take up K slowly by a process, called TrkF, whose rate of transport is linearly dependent on K concentration up to 105 mM. On the whole, each of these systems appears to function as an independent path for K uptake since the kinetics of uptake when two are present is the sum of each operating alone. This is not true for strains having both the TrkD and Kdp systems, where presence of the latter results in K uptake which saturates at a K concentration well below 0.1 mM. This result indicates some interaction between these systems so that uptake now has the affinity characteristic of the Kdp system. All transport systems are able to extrude Na during K uptake. The measurements of cell Na suggest that growing cells of E. coli have very low concentrations of Na, considerably lower than indicated by earlier studies.

Effect of Li and of other ions on Na transport in epithelial cells of frog skin

1980 ◽  
Vol 29 (16) ◽  
pp. 2265-2268 ◽  
Author(s):  
Thomas U.L. Biber ◽  
Terry L. Mullen
Keyword(s):  
Epithelial Cells ◽  
Frog Skin ◽  
Na Transport

scholarly journals Interaction between the Effects of Inside and Outside Na and K on Bullfrog Skin Potential

1965 ◽  
Vol 49 (2) ◽  
pp. 309-320 ◽  
Author(s):  
Daniel E. Leb ◽  
Charles Edwards ◽  
Barry D. Lindley ◽  
T. Hoshiko ◽  
Keyword(s):  
Ionic Strength ◽  
Frog Skin ◽  
Bathing Solution ◽  
Skin Potential ◽  
Solution Bathing ◽  
Total Ionic Strength ◽  
K Concentration

The composition of the solution bathing one border of the isolated frog skin affects the response of the potential across the skin to changes in the composition of the solution bathing the opposite border. Increasing the K concentration of the inside (corium) bathing solution decreased the sensitivity of the potential to a change in outside Na concentration. Decreasing the outside Na concentration decreased the sensitivity of the potential to a change in inside K concentration. Increasing the total ionic strength of the outside bathing solution or of both bathing solutions decreased the sensitivity of the potential to a change in outside Na concentration.

Factors Involved In the Plasminogen Activation System in Human Breast Tumours

1994 ◽  
Vol 71 (05) ◽  
pp. 684-691 ◽  
Author(s):  
László Damjanovich ◽  
Csaba Turzó ◽  
Róza Ádány
Keyword(s):  
Epithelial Cells ◽  
Connective Tissue ◽  
Plasminogen Activators ◽  
Breast Tumour ◽  
Plasminogen Activation ◽  
Malignant Tumours ◽  
Plasminogen Activation System ◽  
Activation System ◽  
Malignant Breast ◽  
Pai 1

SummaryThe plasminogen activation system is a delicately balanced assembly of enzymes which seems to have primary influence on tumour progression. The conversion of plasminogen into serine protease plasmin with fibrinolytic activity depends on the actual balance between plasminogen activators (urokinase type; u-PA and tissue type; t-PA) and their inhibitors (type 1 and 2 plasminogen activator inhibitors; PAI-1 and PAI-2). The purpose of this study was to determine the exact histological localization of all the major factors involved in plasminogen activation, and activation inhibition (plasmin system) in benign and malignant breast tumour samples. Our results show that factors of the plasmin system are present both in benign and malignant tumours. Cancer cells strongly labelled for both u-PA and t-PA, but epithelial cells of fibroadenoma samples were also stained for plasminogen activators at least as intensively as tumour cells in cancerous tissues. In fibroadenomas, all the epithelial cells were labelled for PAM. Staining became sporadic in malignant tumours, cells located at the periphery of tumour cell clusters regularly did not show reaction for PAI-1. In the benign tumour samples the perialveolar connective tissue stroma contained a lot of PAI-1 positive cells, showing characteristics of fibroblasts; but their number was strongly decreased in the stroma of malignant tumours. These findings indicate that the higher level of u-PA antigen, detected in malignant breast tumour samples by biochemical techniques, does not necessarily indicate increased u-PA production by tumour cells but it might be owing to the increased number of cells producing u-PA as well. In malignant tumours PAI-1 seems to be decreased in the frontage of malignant cell invasion; i.e. malignant cells at the host/tumour interface do not express PAI-1 in morphologically detectable quantity and in the peritumoural connective tissue the number of fibroblasts containing PAI-1 is also decreased.

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