Chloride passage across the isolated skin of the toad Bufo arenarum.

ORCE G.,; CASTILLO G.; CHANAMPA Y.; RAZOUK G.

Rosario (Pcia de Santa fe)

Congreso; XLI Reunión Anual de la Sociedad Argentina de Farmacología Experimental (SAFE); 2009

Sociedad Argentina de Farmacología Experimental (SAFE)

Chloride passage across the isolated skin of the toad Bufo arenarum Orce G., Castillo G., Chanampa Y. and Razouk G. Inst. of Physiology, Faculty of Medicine, UNT - Dept. Physiology, INSIBIO (UNT-CONICET) Junín 1229, 4000 Tucumán - orcegap@yahoo.com   Cl- transport across membranes bears great importance to body fluid management, Cl- being the main anion in the extracellular compartment. We found in the isolated toad skin a Cl- channel whose characteristics set it apart from others described in the literature. The channel is activated by exposure to theophylline or cAMP, but not to oxytocin or norepinephrine. It can be activated in the absence of apical Cl-, and supports Cl- flux in either direction, which can be measured when exposed to a [Cl-] gradient as a gradient-generated short circuit current (SCCg). It is permeable to Cl-, Br-, I- and 99mTcO4- in a different pattern than observed following permeabilization of tight junctions by apical hypertonicity. The channel is inactivated by exposure of the skin to dinitrophenol or rotenone; in the latter case, inhibition is overcome by addition of succinate to the bath, thus confirming dependence on cell metabolism. In the absence of an osmotic gradient, exposure of the theophylline-treated skin to a [Cl-] gradient generates a water flow following the gradient. The channel is a high-volume Cl- passage pathway and may be involved in the maintenance of the body’s ionic and osmotic balance. The lack of activation by oxytocin or norepinephrine indirectly supports the hypothesis of compartmentalization of cAMP production following receptor stimulation.