In vivo treatment of bullfrog tadpoles with aldosterone potentiates ACh-receptor channels, but not amiloride-blockable Na+ channels in the skin.
Amiloride-blockable Na(+) channels participate in active Na(+) transport across adult, but not larval, bullfrog skin. Their development is induced in vitro by culturing the tadpole skin with aldosterone. When tadpoles were raised in aldosterone (5 x 10(-7) M) for 2 weeks, however, neither development of such channels nor localization of antigen A, a marker of adult-type epidermis, was seen, the skin still being of the larval type. In contrast, aldosterone treatment did potentiate (by a factor of two) the activity of the acetylcholine receptor (ACh-receptor) channel, a functional marker of larval-type skin. The short-circuit current (SCC) across the skin, far from being inhibited by amiloride, was stimulated by both amiloride and ACh. The nystatin-stimulated SCC was about twice its control amplitude, suggesting that the aldosterone treatment also potentiated the activity of the Na(+) pump.
Takada
M
M
Department of Physiology, Saitama Medical School, Japan.
Yai
H
H
Komazaki
S
S
D000450:Aldosterone / Q000494:pharmacology*; D000584:Amiloride / Q000494:pharmacology*; D000818:Animals; D001693:Biological Transport, Active; D018679:Cholinergic Agonists / Q000494:pharmacology*; D066298:In Vitro Techniques; D007814:Larva / Q000187:drug effects* / Q000378:metabolism; D011892:Rana catesbeiana; D012867:Skin / Q000187:drug effects* / Q000378:metabolism; D012964:Sodium / Q000378:metabolism; D062687:Sodium Channel Agonists; D026941:Sodium Channel Blockers; D015222:Sodium Channels / Q000378:metabolism
D018679:Cholinergic Agonists; D062687:Sodium Channel Agonists; D026941:Sodium Channel Blockers; D015222:Sodium Channels; D000450:Aldosterone; D000584:Amiloride; D012964:Sodium