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Inhibition of olfactory cyclic nucleotide‐activated current by calmodulin antagonists
Author(s) -
Kleene Steven J.
Publication year - 1994
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/j.1476-5381.1994.tb14760.x
Subject(s) - calmodulin , cyclic gmp , cyclic nucleotide gated ion channel , olfactory receptor , nucleotide , cyclic nucleotide , neuroscience , chemistry , olfaction , pharmacology , biology , microbiology and biotechnology , biochemistry , enzyme , gene
1 In amphibian olfactory receptor neurones, much of the depolarizing current in response to odours is carried by cationic channels that are directly gated by cyclic AMP. The effects of four calmodulin antagonists on the cyclic AMP‐activated receptor current were studied in single olfactory cilia of the frog. 2 Two antagonists, W‐7 and trifluoperazine, were potent and reversible inhibitors of the cyclic AMP‐activated current. IC 50 values were 5 μ m for W‐7 and 13 μ m for trifluoperazine. A third antagonist, calmidazolium, irreversibly blocked the current. The fourth, mastoparan, had little effect. 3 Calmodulin was unable to reverse the effects of W‐7 and trifluoperazine, suggesting that these inhibitors act directly on the cyclic AMP‐gated channels. 4 Neither W‐7 nor trifluoperazine inhibited a Ca 2+ ‐activated Cl − current which also contributes to the odorant response. These compounds thus allow the two components of the olfactory receptor current to be discriminated.