Kinetics of ionic transport across frog skin: Two concentration-dependent processes

1980 ◽  
Vol 56 (2) ◽  
pp. 139-147 ◽  
Author(s):  
J. Ehrenfeld ◽  
F. Garcia-Romeu
Keyword(s):  
Frog Skin ◽  
Ionic Transport ◽  
Kinetics Of ◽  
Dependent Processes

Stratum corneum of frog skin: inferences for studies of Na entry and transport pool

1977 ◽  
Vol 232 (1) ◽  
pp. 37-44 ◽  
Author(s):  
S. I. Helman ◽  
R. S. Fisher
Keyword(s):  
Stratum Corneum ◽  
Preliminary Data ◽  
Frog Skin ◽  
Tissue Water ◽  
Mean Values ◽  
Sodium Uptake ◽  
Kinetics Of ◽  
Total Sodium

Pieces of isolated stratum corneum from frog skins were studied. Preliminary data showed that approximately 56% of the total sodium of split skins was associated with the stratum corneum. In more detailed studies, the sodium space estimated with 22Na and the volume of tissue water were identical, averaging 0.95 mul/cm2. Thus, the stratum corneum contained approximately 0.11 mueq Na+/cm2. Similar determinations of the sucrose, mannitol, and inulin spaces of the stratum corneum gave mean values of 0.84, 2.21, and 1.84 mul/cm2, respectively. Surprisingly, the mannitol and inulin spaces were observed to be at least twice as large as the space occupied by the tissue water, and this can be interpreted to mean that mannitol and inulin bind in appreciable amounts and thus are unsuitable markers of the sodium space. Whereas the kinetics of sodium uptake and washout could be described simply, similar studies for sucrose, mannitol, and inulin were more complex and consistent with appreciable binding of the substances to the stratum corneum.

scholarly journals A Rayleighian approach for modeling kinetics of ionic transport in polymeric media

2017 ◽  
Vol 146 (6) ◽  
pp. 064902 ◽  
Author(s):  
Rajeev Kumar ◽  
Jyoti P. Mahalik ◽  
Vera Bocharova ◽  
Eric W. Stacy ◽  
Catalin Gainaru ◽  
...  
Keyword(s):  
Ionic Transport ◽  
Kinetics Of ◽  
Polymeric Media

Investigating Kinetics of Temperature-Dependent Processes Using Microfluidics

2006 ◽  
Author(s):  
Philippe Laval ◽  
Jean-Baptiste Salmon ◽  
Galder Cristobal ◽  
Mathieu Joanicot
Keyword(s):  
High Temperature ◽  
Temperature Gradient ◽  
Microfluidic System ◽  
Crystal Nucleation ◽  
Flow Focusing ◽  
Temperature Dependent ◽  
Fast Kinetics ◽  
Oil Flow ◽  
Kinetics Of ◽  
Dependent Processes

We have developed an original microfluidic system to study fast kinetics of temperature-dependent processes in an emulsion. Using flow focusing geometries, aqueous droplets are continuously formed in an oil flow. These droplets, acting as microreactors (100 nL), contain the solution to be investigated, and are formed at high temperature. They flow in a microchannel to a cooled area through a controlled temperature gradient (typically from 60 to 10°C in a few seconds). Along the microchannel, the distance being equivalent to the time thanks to the use of droplets, the kinetics of the process can be followed (from 10 to 300 s). In particular, the microdevice has been used to study the kinetics of crystal nucleation of a solute dispersed in water after a temperature quench.

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.

Electrodiffusion Kinetics of Ionic Transport in a Simple Membrane Channel

2013 ◽  
Vol 117 (46) ◽  
pp. 14283-14293 ◽  
Author(s):  
Ivan Valent ◽  
Pavol Petrovič ◽  
Pavel Neogrády ◽  
Igor Schreiber ◽  
Miloš Marek
Keyword(s):  
Ionic Transport ◽  
Membrane Channel ◽  
Kinetics Of

Saturation kinetics of sodium efflux across isolated frog skin

1976 ◽  
Vol 231 (4) ◽  
pp. 995-1001 ◽  
Author(s):  
TU Biber ◽  
TL Mullen
Keyword(s):  
Active Transport ◽  
Frog Skin ◽  
Apical Cell ◽  
Transport Pathway ◽  
Sodium Efflux ◽  
Saturation Kinetics ◽  
Transcellular Pathway ◽  
Na Efflux ◽  
Edge Damage ◽  
Kinetics Of

Measurement of Na efflux across the frog skin epithelium from the serosal side to the outside (JNa 3 leads to 1) in a new chamber specifically designed to avoid edge damage shows that JNa 3 leads to 1 exhibits saturation kinetics with a maximal efflux (Jmax) of 31.8 nmol/cm2 per h and an apparent KNa of 4.0 mM. In contrast, JNa 3 leads to 1 measured in conventional chambers and efflux determinations in the new chamber of substances that pass the epithelium via extracellular pathways (polyethylene glycol 900, sucrose, mannitol) exhibit a linear relationship between the efflux of the substance in question and its concentration in the bath. In addition, changes in external Na concentration do not cause substantial changes in JNa 3 leads to 1. The saturation remains but both Jmax and KNa increase after application of ouabain. Amiloride, as well as dinitrophenol, eliminates the saturation and JNa 3 leads to 1 becomes a linear function of Na concentration. The separate effects of ouabain and amiloride suggest that these two inhibitors which are known to affect two distinctly different steps in the active transport pathway act also on two separate steps of JNa 3 leads to 1: the passage across the inward- (serosal) and outward-facing (apical) cell membranes of the epithelial cells, respectively. The action of dinitrophenol indicates the involvement of metabolism in JNa 3 leads to 1 probably at the latter of the two steps. The results suggest strongly that JNa 3 leads to 1 proceeds not via a paracellular but via a transcellular pathway that interacts with the active transport pathway.

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