Differentiation of frog skin active Na+ transport during metamorphosis is induced by thyroid hormone.
Hormonal control of differentiation of the active Na+ transport system across the skin of the Rana catesbeiana tadpole during metamorphosis was investigated. Active Na+ transport in the tadpole does not operate before climax stages (stage XX) because of the lack of a Na+ channel, even though the skin already has a Na+ pump. Injection of aldosterone (200 nmol/kg body wt), corticosterone (500 nmol/kg body wt), or hydrocortisone (300 nmol/kg body wt) at stages XIII-XV and administered for 2 weeks neither induced differentiation of the Na+ channel nor stimulated the Na+ pump. On the other hand, differentiation of the Na+ channel (increase in active Na+ transport) was induced by thyroid hormone without supplementary mineralicorticoid or glucocorticoid treatment. Triiodothyronine (10 nmol/kg body wt every other day for 2 weeks) increased Na+ channel density, even when the mineralicorticoid antagonist spironolactone (20 mumol/kg body wt) or glucocorticoid antagonist metyrapon (442 nmol/kg body wt) were injected. The skin active Na+ transport system acquires aldosterone sensitivity only after differentiation of the Na+ channel is induced by thyroid hormone.
Takada
M
M
Department of Physiology, Saitama Medical School, Saitama, Japan.
D000450:Aldosterone / Q000494:pharmacology; D000818:Animals; D001693:Biological Transport, Active / Q000187:drug effects; D003345:Corticosterone / Q000494:pharmacology; D004566:Electrodes; D006854:Hydrocortisone / Q000494:pharmacology; D008675:Metamorphosis, Biological / Q000187:drug effects*; D008797:Metyrapone / Q000494:pharmacology; D009761:Nystatin / Q000494:pharmacology; D011892:Rana catesbeiana; D012867:Skin / Q000187:drug effects / Q000378:metabolism*; D012964:Sodium / Q000378:metabolism*; D013148:Spironolactone / Q000494:pharmacology; D014284:Triiodothyronine / Q000494:pharmacology*
D014284:Triiodothyronine; D009761:Nystatin; D013148:Spironolactone; D000450:Aldosterone; D012964:Sodium; D003345:Corticosterone; D006854:Hydrocortisone; D008797:Metyrapone