Odor responses after complete desensitization of the cAMP-dependent pathway in turtle olfactory cells.

The degree of contribution of the cAMP signal transduction pathway to odor responses was examined by recording current responses from isolated turtle olfactory cells under the whole-cell voltage clamp conditions. The cAMP signal transduction pathway was desensitized by dialyzing 1 mM cAMP and 0.5 mM IBMX from the patch pipette into the cells. Extracellular application of 3 mM cpt-cAMP, a membrane-permeable cAMP analogue elicited no response, indicating that the cAMP pathway was completely desensitized. Application of an odorant cocktail induced a large inward current under these conditions, suggesting that the cAMP-independent signal transduction contributes significantly to generation of odor responses in the turtle.