MODIFICATION OF THE ELECTRICAL POTENTIAL OF FROG SKIN BY ACETYLCHOLINE

1940 ◽  
Vol 130 (3) ◽  
pp. 557-561 ◽  
Author(s):  
T. Cunliffe Barnes
Keyword(s):  
Frog Skin ◽  
Electrical Potential

Effect of furosemide on the electrical parameters of frog skin

1982 ◽  
Vol 243 (6) ◽  
pp. F581-F587 ◽  
Author(s):  
A. Corcia ◽  
S. R. Caplan
Keyword(s):  
Active Transport ◽  
Frog Skin ◽  
Short Circuit ◽  
Electrical Potential ◽  
Short Circuit Current ◽  
Relative Increase ◽  
Electrical Potential Difference ◽  
Electrical Parameters ◽  
Active Conductance ◽  
Solution Bathing

When added to the mucosal solution bathing isolated frog skin at concentrations ranging from 5 X 10(-4) to 3 X 10(-3) M, the diuretic furosemide increased both the active transport of sodium and the electrical potential difference across the tissue in a dose-dependent way. The same effect was observed in chloride-free solutions. Mucosal furosemide also decreased the passive unidirectional fluxes of chloride. We believe that as far as electrical parameters are concerned mucosal furosemide has a double effect in frog skin: it increases the active conductance to sodium across the mucosal membrane, thus increasing active transport, and decreases the passive permeability to chloride, thus altering the passive conductance of the skin. The relative increase in short-circuit current was, however, invariably greater than the increase of the active conductance, suggesting the influence of yet a third effect. The effect of mucosal furosemide on active sodium transport was blocked by amiloride (5 X 1-(-5) M) and was independent of vasopressin. Qualitatively the effect was similar to the effect produced by triphenylmethylphosphonium ion.

scholarly journals Lithium-Induced Oscillations of Potential and Resistance in Isolated Frog Skin

1961 ◽  
Vol 44 (6) ◽  
pp. 1165-1176 ◽  
Author(s):  
Alan Finkelstein
Keyword(s):  
Hydrostatic Pressure ◽  
Phase Shift ◽  
Direct Current ◽  
Frog Skin ◽  
Water Movement ◽  
Electrical Potential ◽  
Lithium Ion ◽  
The Mean ◽  
The Waves ◽  
Hydrostatic Pressure Difference

The rhythmical variations of electrical potential and DC resistance resulting from the exposure of the anatomical outside of isolated frog skin to a concentration of lithium ion greater than 20 millinormal were reinvestigated. In general, the potential and resistance changes were in phase, although in some skins, a phase shift occurred after the first few waves. The mean level of the resistance declined during the exposure to lithium, returning to its former level upon reintroduction of sodium in place of lithium. The oscillations, with a period of from 3 to 15 minutes, could last for 2 hours or more before damping out; the amplitude of the waves could be altered during this time by the passage of direct current or by the introduction of a hydrostatic pressure difference across the skin. Even after the oscillations damped out, the system remained "excitable," responding to a step of direct current or hydrostatic pressure with an oscillatory train. The nature and magnitude of the response to current and pressure were dependent upon the "polarity" of the applied perturbation. Direct observation of the skin revealed no evidence of oscillatory water movement concomitant with the electrical events.

scholarly journals THE EFFECTS OF MAGNESIUM ON NUCLEOSIDE PHOSPHATASE ACTIVITY IN FROG SKIN

1967 ◽  
Vol 33 (2) ◽  
pp. 411-418 ◽  
Author(s):  
Rolf H. Dahl ◽  
James N. Pratley
Keyword(s):  
Cell Membrane ◽  
Frog Skin ◽  
Short Circuit ◽  
Electrical Potential ◽  
Short Circuit Current ◽  
Spectrophotometric Analysis ◽  
Electrical Potential Difference ◽  
Ion Pump ◽  
Pump System ◽  
Nucleoside Triphosphatase

Histochemical tests, employing the Wachstein-Meisel medium, indicate that nucleoside triphosphatase activity is found predominantly in two areas of the frog skin epidermis: (1) in mitochondria, where activity is enhanced by dinitrophenol, Mg2+ dependent, but inhibited by fixation; and (2) apparently associated with cell membranes of the middle and outer portions of the epidermis, where activity is inhibited by Mg2+, unaffected by dinitrophenol, and only slightly reduced by fixation. Spectrophotometric analysis shows that Mg2+ in the medium does not increase spontaneous hydrolysis of ATP, thus obviating the possible explanation that changes in substrate concentrations in the medium lead to alterations in the "staining" distributions. It is postulated that perhaps the two enzymes differ in their requirements for substrate—one requiring the polyphosphate to be in complexed form with Mg2+, the other uncomplexed. Concentrations of Mg2+ required to inhibit cell membrane nucleoside triphosphatase activity also inhibit the electrical potential difference and short-circuit current of the frog skin. Although these observations might be taken as presumptive evidence of the cell membrane enzyme as a component of the ion pump system, because of certain dissimilarities with respect to the biochemists' "transport ATPase" and for other reasons discussed in the paper, any definite conclusions in this regard are premature.

scholarly journals SUMMATION OF ELECTRICAL POTENTIAL OF LIVING MEMBRANES (FROG SKIN): A MODEL OF THE ELECTRICAL ORGAN OF FISHES

1940 ◽  
Vol 23 (6) ◽  
pp. 729-732
Author(s):  
T. Cunliffe Barnes
Keyword(s):  
Frog Skin ◽  
Electrical Potential ◽  
Electrical Fields ◽  
Ringer’S Solution ◽  
In Series

Frog skins arranged "in series" in tubes of Ringer's solution exhibit summation of electrical potential which helps to explain the nature of electrical fields in the organism as a whole and in the electrical organ of fishes. See PDF for Structure

scholarly journals Energetics of Sodium Transport in Frog Skin

1972 ◽  
Vol 59 (1) ◽  
pp. 77-91 ◽  
Author(s):  
F. L. Vieira ◽  
S. R. Caplan ◽  
A. Essig
Keyword(s):  
Free Energy ◽  
Oxygen Consumption ◽  
Sodium Transport ◽  
Frog Skin ◽  
Short Circuit ◽  
Electrical Potential ◽  
Short Circuit Current ◽  
Electrical Potential Difference ◽  
Rate Of Oxygen Consumption ◽  
Phenomenological Coefficients

Studies were made of the dependence of the rate of oxygen consumption, Jr, on the electrical potential difference, Δψ, across the frog skin. After the abolition of sodium transport by ouabain the basal oxygen consumption was independent of Δψ. In fresh skins Jr was a linear function of Δψ over a range of at least ±70 mv. Treatment with aldosterone stimulated the short-circuit current, Io, and the associated rate of oxygen consumption, Jro, and increased their stability; linearity was then demonstrable over a range of ±160 mv. Brief perturbations of Δψ (±30–200 mv) did not alter subsequent values of Io. Perturbations for 10 min or more produced a "memory" effect both with and without aldosterone: accelerating sodium transport by negative clamping lowered the subsequent value of Io; positive clamping induced the opposite effect. Changes in Jro were more readily detectable in the presence of aldosterone; these were in the same direction as the changes in Io. The linearity of Jr in Δψ indicates the validity of analysis in terms of linear nonequilibrium thermodynamics—brief perturbations of Δψ appear to produce no significant effect on either the phenomenological coefficients or the free energy of the metabolic driving reaction. Hence it is possible to evaluate this free energy.

Microelectrode studies of the effect of lanthanum on the electrical potential and resistance of outer and inner cell membranes of isolated frog skin

1982 ◽  
Vol 66 (1) ◽  
pp. 123-132 ◽  
Author(s):  
H. Goudeau ◽  
J. Wietzerbin ◽  
E. Mintz ◽  
M. P. Gingold ◽  
W. Nagel
Keyword(s):  
Frog Skin ◽  
Cell Membranes ◽  
Electrical Potential
Sign in / Sign up

Export Citation Format

Share Document