Frog ANP increases the amiloride-sensitive Na(+) channel activity in urinary bladder cells of Japanese tree frog, Hyla japonica.
We examined the mechanism of amiloride-sensitive Na(+) channels (ENaC) activated by fANP in epithelial cells of frog urinary bladder by using a cell-attached patch-clamp technique. ENaC activities in the epithelial cells were significantly increased following administration of both 10(-9)M fANP and 10(-5)M 8-Br-cGMP. Both fANP and 8-Br-cGMP, however, failed to activate the ENaC in the presence of 10(-6)M amiloride. In addition, 8-Br-cGMP failed to activate the ENaC in the presence of a PKA inhibitor, KT-5720. In the next experiment, we measured both cGMP and cAMP production levels after treatment of fANP on the frog urinary bladder cells. Frog ANP significantly increased cGMP production, but not the cAMP production. Taken together, these results suggest that fANP activates ENaC through increases in cGMP production and activation of PKA.
Yamada
Toshiki
T
Department of Life and Environmental Science, Graduate School of Science and Engineering, University of Toyama, Toyama 930-8555, Japan.
Matsuda
Kouhei
K
Uchiyama
Minoru
M
D000818:Animals; D001001:Anura / Q000378:metabolism*; D009320:Atrial Natriuretic Factor / Q000378:metabolism*; D000242:Cyclic AMP / Q000378:metabolism; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D006152:Cyclic GMP / Q000378:metabolism; D004847:Epithelial Cells / Q000166:cytology / Q000502:physiology*; D053503:Epithelial Sodium Channels / Q000378:metabolism*; D005260:Female; D008297:Male; D018408:Patch-Clamp Techniques; D001743:Urinary Bladder / Q000166:cytology*
D053503:Epithelial Sodium Channels; D009320:Atrial Natriuretic Factor; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases; D006152:Cyclic GMP