title: Effect of mercuric chloride on electrical parameters and anion fluxes in the toad skin.
abstract: The amphibian skin, widely used for studying the transepithelial passage of electrolytes, exhibits anion pathways relatively specific for Cl(-). We studied the effect of HgCl(2), 1.0 x 10(-4) M on its electrical parameters and unidirectional anion fluxes. In the presence of Cl(-), the transepithelial conductance (G) of the isolated skin of the Bufo arenarum toad increased considerably following exposure to HgCl(2), whereas short-circuit current (SCC)--reflecting transepithelial Na(+) transport-underwent only slight stimulation. Following the blockade of Na(+) intake by amiloride, 1.0 x 10(-4) M, the removal of Cl(-) 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 Cl(-) along its gradient. Addition of mercaptoethanol, 5.0 x 10(-3) M to the bath containing Hg(2+) fully reversed these effects. The increase in G was accompanied by an increase in the unidirectional (epidermal to dermal) fluxes of (36)Cl(-) and (131)I(-), and a decrease in the passage of (99m)TcO(4)(-). These results show the effects of HgCl(2) to be similar to those of theophylline, although exhibiting a different selectivity. Our data suggest that anion passage following exposure to HgCl(2) is, like that stimulated by theophylline, predominantly if not exclusively transcellular, and does not involve a significant opening of the tight junctions.
authors.affiliation: Departamento de Fisiología y Neurociencia, INSIBIO (UNT-CONICET), Instituto de Fisiología-Facultad de Medicina, Tucumán, Argentina.
authors.forename: Graciela
authors.initials: G
authors.lastname: Castillo
authors.forename: Yolanda
authors.initials: Y
authors.lastname: Chanampa
authors.forename: Gabriel
authors.initials: G
authors.lastname: Orce
mesh_terms: D000818:Animals; D027321:Anion Transport Proteins / Q000502:physiology*; D002022:Bufo arenarum; D004553:Electric Conductivity; D066298:In Vitro Techniques; D008627:Mercuric Chloride / Q000494:pharmacology*; D012869:Skin Absorption / Q000187:drug effects* / Q000502:physiology
chemical_list: D027321:Anion Transport Proteins; D008627:Mercuric Chloride