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The identification of apparently novel cyclic AMP and cyclic GMP phosphodiesterase activities in guinea‐pig tracheal smooth muscle
Author(s) -
Burns Fiona,
Stevens Patricia A.,
Pyne Nigel 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.tb16164.x
Subject(s) - zaprinast , phosphodiesterase , rolipram , calmodulin , phosphodiesterase inhibitor , smooth muscle , calcium , endocrinology , pde10a , stimulation , phosphodiesterase 3 , medicine , guinea pig , chemistry , muscle contraction , cyclic nucleotide , biochemistry , enzyme , biology , nucleotide , gene
Phosphodiesterase (PDE) activities that were capable of hydrolysing cyclic AMP ( K m = 6.8 ± 2 μ m ) and cyclic GMP ( K m = 6.7 ± 1.6 μ m ) were isolated from tracheal smooth muscle. These enzyme(s) activities were insensitive to stimulation by calcium/calmodulin and to inhibition by cyclic GMP, rolipram (type IV inhibitor) and siguazodan (type III inhibitor). Zaprinast was a relatively poor inhibitor of both cyclic AMP and cyclic GMP hydrolysis (IC 50 = 46 ± 9 μ m and 45 ± 14 μ m respectively). These results suggest that tracheal smooth muscle may contain an apparently novel PDE. However, KCl (30 m m ) which facilitates calcium entry in cells, depressed bradykinin‐stimulated intracellular cyclic AMP formation, suggesting that the type I PDE may be functionally present. We suggest that considerable caution be exercised in identifying apparently novel PDE isoforms.