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Journal of Experimental Biology, Vol 203, Issue 13 2039-2045, Copyright © 2000 by Company of Biologists

JOURNAL ARTICLES

Chloride conductance across toad skin: effects of ionic acclimations and cyclic AMP and relationship to mitochondria-rich cell density

A Rozman, S Gabbay and U Katz
Department of Biology, Technion, Israel Institute of Technology, Haifa, Israel.

The anionic conductance across toad (Bufo viridis) skin was studied using the voltage-clamp technique following long-term (more than 10 days) acclimation to NaCl and KCl solutions. The non-specific baseline conductance was approximately 0.6 mS cm(-)(2) and was similar in skins from all acclimation conditions. The voltage-activated Cl(-) conductance (G(Cl)) was maximal in skins from distilled-water- and KCl-acclimated toads (>3 mS cm(-)(2)) and was greatly reduced following acclimation to NaCl solutions. Cyclic AMP (EC(50)=13 micromol l(-)(1)) and isobutylmethyl xanthine (IBMX) (EC(50)=69 micromol l(-)(1)) exerted different effects on the activated conductance. IBMX only sensitized the activated conductance, whereas cyclic AMP (CPTcAMP) at high concentrations induced an increase in anionic conductance that was insensitive to electrical potential. Furthermore, external Cl(-) was not required for the stimulatory effect of cyclic AMP, and the conductive pathway had low selectivity. The effects of the two agonists were reversible and depended on the acclimation conditions. Following electrical measurements, the skin of the toads was removed and stained with silver to measure mitochondria-rich cell density (D(mrc)). There was no correlation between D(mrc) and Cl(-) conductance in the present study.

This article has been cited by other articles:

				W. Nagel and U. Katz Xanthine derivatives without PDE effect stimulate voltage-activated chloride conductance of toad skin Am J Physiol Cell Physiol, February 1, 2003; 284(2): C521 - C527. [Abstract] [Full Text] [PDF]