Effects of cyclic AMP and theophylline on chloride conductance across toad skin

The Journal of Physiology
U Katz, W Nagel

Abstract

1. The effects of the phosphodiesterase inhibitors theophylline and isobutylmethylxanthine (IBMX) on baseline and voltage-activated Cl- conductance (gCl) of toad skin were compared with those of the potent 2-chlorophenylthio analogue of cAMP (CPT-cAMP). 2. Using intact and split skins of Bufo viridis we confirmed that theophylline and IBMX raised the voltage-activated gCl with a pattern identical to that seen under control conditions. This effect was small or missing if gCl was already high in the control. 3. CPT-cAMP, in contrast, increased the Cl(-)-specific conductance by up to 6 mS cm-2 at short circuit. The characteristic time-dependent, slow activation of gCl by serosa-positive clamp potentials was completely lost under these conditions. 4. Coinciding with the loss of voltage activation of gCl the plateau value of the Lorentzian component of fluctuation in current at serosa-positive clamp potentials decreased by almost 50%. The corner frequencies were not notably different. 5. After CPT-cAMP, the sigmoidal voltage-conductance relation that is characteristic of control conditions or after theophylline disappeared; the patterns were variable and incompatible with voltage activation. 6. The voltage-activated gCl under contro...Continue Reading

Citations

Mar 29, 2005·Comparative Biochemistry and Physiology. Toxicology & Pharmacology : CBP·Graciela CastilloGabriel Orce
Oct 4, 2011·General and Comparative Endocrinology·Edison S M CarvalhoDeborah M Power
Jul 5, 2008·Comparative Biochemistry and Physiology. Part A, Molecular & Integrative Physiology·A RozmanW Nagel
Nov 8, 2002·Biochimica Et Biophysica Acta·Niels J WillumsenE Hviid Larsen
Nov 7, 2006·Veterinary Dermatology·David McEwan JenkinsonDouglas L Bovell
Oct 25, 2002·American Journal of Physiology. Cell Physiology·Wolfram Nagel, Uri Katz
Sep 8, 2001·American Journal of Physiology. Cell Physiology·W NagelU Katz

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