Passive Cl- Currents in Toad Skin: Potential Dependence and Relation to Mitochondria-Rich Cell Density

1987 ◽  
pp. 20-30 ◽  
Author(s):  
N. J. Willumsen ◽  
E. Hviid Larsen
Keyword(s):  
Cell Density ◽  
Toad Skin ◽  
Skin Potential ◽  
Potential Dependence

scholarly journals Electrical Potential Profile of the Toad Skin Epithelium

1964 ◽  
Vol 47 (4) ◽  
pp. 795-808 ◽  
Author(s):  
Guillermo Whittembury
Keyword(s):  
Phase Contrast ◽  
Electrical Potential ◽  
Potential Difference ◽  
Potential Profile ◽  
Outer Side ◽  
Toad Skin ◽  
Skin Potential ◽  
Contrast Microscopy ◽  
Toad Skin Epithelium

The electrical potential profile of the isolated toad skin was recorded, in vitro, by impalement with micropipette-electrodes, when both sides of the skin were bathed with sulfate-Ringer. The outer side of the skin was some 110 mv negative with respect to the inner side. Upon impalement from the outer side, two main positive steps of 40 to 70 mv each were found to form the skin potential. The site of measurement of each potential difference was permanently marked in the tissue during recording, by deposition of carmine from the micropipette tip using iontophoresis. Serial histological sections of the skin were prepared and search was then made of the carmine deposits 2 to 6 µ in size, under phase contrast microscopy. By this method the main steps were located at the outer and the inner sides of the stratum germinativum cells. The DC resistances between the micropipette tip and the bathing solutions were measured during the recording of each potential difference. The resistance at the outer side of the stratum germinativum cells, of 1.09 kilohm. cm2, was larger than that at their inner side, of 0.30 kilohm. cm2. The stratum germinativum cells maintained a potential difference of -34 mv during short-circuiting of the skin.

Chloride conductance across toad skin: effects of ionic acclimations and cyclic AMP and relationship to mitochondria-rich cell density

2000 ◽  
Vol 203 (13) ◽  
pp. 2039-2045
Author(s):  
A. Rozman ◽  
S. Gabbay ◽  
U. Katz
Keyword(s):  
Cyclic Amp ◽  
Cell Density ◽  
Electrical Potential ◽  
Electrical Measurements ◽  
Toad Skin ◽  
Conductive Pathway ◽  
High Concentrations ◽  
Toad Bufo ◽  
Cl Conductance

The anionic conductance across toad (Bufo viridis) skin was studied using the voltage-clamp technique following long-term (more than 10 days) acclimation to NaCl and KCl solutions. The non-specific baseline conductance was approximately 0.6 mS cm(−)(2) and was similar in skins from all acclimation conditions. The voltage-activated Cl(−) conductance (G(Cl)) was maximal in skins from distilled-water- and KCl-acclimated toads (>3 mS cm(−)(2)) and was greatly reduced following acclimation to NaCl solutions. Cyclic AMP (EC(50)=13 micromol l(−)(1)) and isobutylmethyl xanthine (IBMX) (EC(50)=69 micromol l(−)(1)) exerted different effects on the activated conductance. IBMX only sensitized the activated conductance, whereas cyclic AMP (CPTcAMP) at high concentrations induced an increase in anionic conductance that was insensitive to electrical potential. Furthermore, external Cl(−) was not required for the stimulatory effect of cyclic AMP, and the conductive pathway had low selectivity. The effects of the two agonists were reversible and depended on the acclimation conditions. Following electrical measurements, the skin of the toads was removed and stained with silver to measure mitochondria-rich cell density (D(mrc)). There was no correlation between D(mrc) and Cl(−) conductance in the present study.

scholarly journals The effect of noradrenaline on the toad skin potential

1970 ◽  
Vol 209 (3) ◽  
pp. 513-537 ◽  
Author(s):  
C. R. House
Keyword(s):  
Toad Skin ◽  
Skin Potential

Increassed parietal cell density in patients with perfurated duodenal ulcer: Comparison with non-complicated duodenal ulcer patients

2001 ◽  
Vol 120 (5) ◽  
pp. A250-A250
Author(s):  
A BARBOSA ◽  
C MENDES ◽  
L COELHO ◽  
C RODRIGUES ◽  
M MACHADO ◽  
...  
Keyword(s):  
Duodenal Ulcer ◽  
Cell Density ◽  
Parietal Cell

Comparative Study of Size, Total Protein, Fibrinogen and 5-HT Content of Human and Canine Platelet Density Subpopulations

1986 ◽  
Vol 56 (03) ◽  
pp. 288-292 ◽  
Author(s):  
Diego Mezzano ◽  
Eduardo Aranda ◽  
Arnaldo Foradori
Keyword(s):  
Comparative Study ◽  
Protein Content ◽  
Cell Density ◽  
Total Protein ◽  
Unit Volume ◽  
Low Density ◽  
Dense Bodies ◽  
Artifactual Changes ◽  
Platelet Release ◽  
The Difference

SummaryThe size, total protein, fibrinogen and 5-HT content were evaluated in density subpopulations of human and canine platelets fractionated in linear arabinogalactan gradients. The methodology was assessed to ascertain that platelet separation was by density and to discard artifactual changes and platelet release during the procedure. EDTA or PGEi increased the size of human PRP-platelets, but not of dog platelets. In humans, high density (HD) platelets were 1.26 times larger and contained 1.88 times more fibrinogen, 2.23 times more 5-HT and 1.37 times more protein than low density (LD) platelets; in dogs, these density cohorts did not differ in protein content, but LD platelets were 1.29 times larger and had 1.33 times more fibrinogen and 5-HT than HD platelets. These findings suggest that cell density is mostly dependent on the protein content per unit volume of platelets (and not on dense bodies). The differences in fibrinogen and 5-HT content between HD and LD cohorts in humans and dogs may be related to platelet age. The difference in volume between HD and LD platelets in dogs is of uncertain interpretation.

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