Effect of calcium on development of amiloride-blockable Na+ transport in axolotl in vitro.
The axolotl, Ambystoma mexicanum, which has no specific calcium-containing sieve layer in the dermis, provides useful material for the study of the effect of Ca2+ on the development of amiloride-blockable active Na+ transport across the skin of amphibians. We raised axolotls in thyroid hormone or aldosterone or cultured the skin with corticoid plus one of several Ca2+ concentrations and found that 1) although the short-circuit current (SCC) was increased by both aldosterone and 3,3',5-triiodo-L-thyronine in vivo, only corticoid was necessary for such an increase in vitro; 2) the development of the SCC in vitro was both corticoid and Ca2+ dependent, because the SCC was well developed with over 100 microM Ca2+ but not with under 10 microM Ca2+ in the presence of corticoid, nor even with 300 microM Ca2+ without corticoid; and 3) Ca2+, but not corticoid, was necessary for the formation of cell-to-cell junctions, because the resistance of the skin was well developed with 300 microM Ca2+ without corticoid.
Department of Physiology, Saitama Medical School, Moroyama, Iruma-gun, Saitama 350-04 Japan.
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M
Takada
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H
Yai
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S
Komazaki
D000450:Aldosterone / Q000494:pharmacology; D000558:Ambystoma mexicanum; D000584:Amiloride / Q000494:pharmacology*; D000818:Animals; D001693:Biological Transport, Active / Q000187:drug effects / Q000502:physiology; D002118:Calcium / Q000494:pharmacology*; D004492:Edetic Acid / Q000494:pharmacology; D004553:Electric Conductivity; D007814:Larva; D009924:Organ Culture Techniques; D010042:Ouabain / Q000494:pharmacology; D012867:Skin / Q000187:drug effects / Q000378:metabolism*; D012879:Skin Physiological Phenomena / Q000187:drug effects; D012964:Sodium / Q000378:metabolism*; D013997:Time Factors; D014284:Triiodothyronine / Q000494:pharmacology
D014284:Triiodothyronine; D000450:Aldosterone; D010042:Ouabain; D000584:Amiloride; D004492:Edetic Acid; D012964:Sodium; D002118:Calcium