Prolactin increases open-channel density of epithelial Na+ channel in adult frog skin
Makoto Takada* and
Miyoko Kasai
Department of Physiology, Saitama Medical School, Moroyama,
Iruma-gun, Saitama, 3500495 Japan
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Fig. 4. Blocker-dependent changes in 2 fc (see Equation 2)
and short-circuit current (i). The blocking K01
and and unblocking K10 coefficients for CDPC are
determined from the slope and intercept on the ordinate of corner-frequency
plots (A). The single-channel current was calculated by extrapolation of the
CDPC concentration versus i curve to the ordinate (B). Values are
means ± S.E.M.; N=9.
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Fig. 1. A typical example of the effect of prolactin (PRL) on short-circuit current
(SCC) I tree frog skin (inset shows data for the initial phase of response).
Values are means ± S.E.M.; N = number of experiments. PRL (10
µg ml-1) was applied to the basolateral side of the skin and
amiloride (Am; 10-4 mol l-1) to the apical side, at the
times shown.
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Fig. 2. Typical examples of effect of CDPC in the presence or absence of prolactin
(PRL). CDPC (50-800 µmol l-1) was applied to the apical side of
tree frog skin at the indicated times and the current-noise power-density
spectra were measured at each concentration of CDPC (control condition). CDPC
was then washed from the apical side (`wash'). Next, PRL (10 µg
ml-1) was applied to the basolateral side of the skin and CDPC
(50-800 µmol l-1) was again applied to the apical side. The
current-noise power-density spectra were measured at each concentration of
CDPC (PRL condition). At the end of the experiment, amiloride (Am;
10-4 mol l-1) was applied to the apical side to allow
measurement of the amiloride-insensitive SCC.
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Fig. 3. Summary of effect of prolactin (PRL; 10 µg ml-1) on
short-circuit current (SCC; i), Na+ channel density
(M), K01 and K10 (blocking
and unblocking rate coefficients, respectively) and Km of
adult skin of tree frog. Values are means ± S.E.M.; N=9.
Asterisks show a significant difference (P<0.05) from control
values (before PRL).
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© The Company of Biologists Ltd 2003
