Cyclic nucleotide-dependent phosphodiesterases (PDEI) inhibition by muscarinic antagonists in bovine tracheal smooth muscle.

In bovine tracheal smooth muscle (TSM) strips, muscarinic antagonists (atropine, 4-DAMP, AFDX-116 and methoctramine) were able to increase simultaneously and a similar fashion the intracellular levels of cyclic nucleotides, with a cAMP/cGMP ratio higher than 2.0. These original pharmacological responses were time-and dose-dependent, exhibiting maximal values at 15 min, with a pEC(50) of 7.