The Isoenzyme Selectivity of AH 21–132 as an Inhibitor of Cyclic Nucleotide Phosphodiesterase Activity

Abstract

The smooth muscle relaxant, AH 21–132, was tested for its inhibitory effect on the cyclic nucleotide phosphodiesterase (PDE) activities fractionated from guinea-pig cardiac ventricle and bovine trachealis muscle. Both tissues yielded significant PDE-I and PDE-II activities. The cardiac ventricle also contained a significant amount of PDE-III whilst the trachealis contained PDE-IV. AH 21–132 inhibited PDE-III and PDE-IV selectively (K_i values 0.30–0.55 μM) compared with PDE-I and PDE-II (K_i values 20–140μM).

Key Words: :

• Cyclic nucleotides
• phosphodiesterase
• trachea
• heart