Capacitance,short-circuit current and osmotic water flow across different regions of the isolated toad skin |
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Authors: | Cathleen A Baker Stanley D Hillyard |
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Institution: | (1) Department of Biological Sciences, University of Nevada, Las Vegas, 89154 Las Vegas, NV, USA |
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Abstract: | Summary The amphibian antidiuretic hormone, arginine vasotocin, stimulated osmotic water flow across isolated skin from the pelvic but not the pectoral skin of the toad, Bufo woodhouseii. Changes in the apical membrane capacitance were not observed for either region of the skin following treatment with arginine vasotocin when there was an osmotic gradient across the tissue. In the absence of an osmotic pressure gradient, the apical membrane capacitance of the pelvic skin increased from 2.8±0.5 to 3.3±0.6 F · cm-2 after treatment with 5 · 10-8
M arginine vasotocin. Under these conditions, apical membrane capacitance of the pectoral skin was 1.8±0.1 F · cm-2 and did not change significantly after arginine vasotocin treatment. The amiloride-sensitive short-circuit current across the pelvic skin was stimulated by arginine vasotocin as was the density of channels in the apical membrane as determined by fluctuation analysis. Values for channel density in the pelvic skin also correlated with apical membrane capacitance and increased from 90 to 273 channels per m2 of estimated membrane area following arginine vasotocin treatment. In the pectoral skin the stimulation of short-circuit current following arginine vasotocin treatment was small and an increase in channel density could not be demonstrated. The current through single Na+ channels in both regions of the skin did not different either before or after arginine vasotocin treatment.Abbreviations A
amiloride
- ADH
antidiuretic hormone
- AVT
arginine vasotocin
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C
capacitance
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C
a
capacitance of apical membrane
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f
c
corner frequency
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i
single-channel current
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osmotic water flow
- IMP
intramembrane particles
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I
sc
short-circuit current
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amiloride-sensitive short-circuit current
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M
channel density
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P
o
probability of a channel being open
- R
channel receptor
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R
a
apical resistance
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R
p
paracellular resistance |
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Keywords: | Skin Sodium transport Water flux Arginine vasotocin Capacitance Toad Bufo woodhouseii |
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