Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
10821820 | Comparative Biochemistry and Physiology Part C: Toxicology & Pharmacology | 2005 | 7 Pages |
Abstract
The amphibian skin, widely used for studying the transepithelial passage of electrolytes, exhibits anion pathways relatively specific for Clâ. We studied the effect of HgCl2, 1.0Ã10â4 M on its electrical parameters and unidirectional anion fluxes. In the presence of Clâ, the transepithelial conductance (G) of the isolated skin of the Bufo arenarum toad increased considerably following exposure to HgCl2, whereas short-circuit current (SCC)-reflecting transepithelial Na+ transport-underwent only slight stimulation. Following the blockade of Na+ intake by amiloride, 1.0Ã10â4 M, the removal of Clâ from the solution bathing the epidermal border of the skin brought about a decrease in G, and gave rise to a gradient-induced SCC (SCCg) consistent with transepithelial passage of Clâ along its gradient. Addition of mercaptoethanol, 5.0Ã10â3 M to the bath containing Hg2+ fully reversed these effects. The increase in G was accompanied by an increase in the unidirectional (epidermal to dermal) fluxes of 36Clâ and 131Iâ, and a decrease in the passage of 99mTcO4â. These results show the effects of HgCl2 to be similar to those of theophylline, although exhibiting a different selectivity. Our data suggest that anion passage following exposure to HgCl2 is, like that stimulated by theophylline, predominantly if not exclusively transcellular, and does not involve a significant opening of the tight junctions.
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Authors
Graciela Castillo, Yolanda Chanampa, Gabriel Orce,