Cyclic nucleotide phosphodiesterase isoenzymes in guinea-pig tracheal muscle and bronchorelaxation by alkylxanthines.
In this study the phosphodiesterase (PDE) isoenzymes in guinea-pig trachealis smooth muscle were separated by DEAE-Sepharose anion exchange chromatography, identified, and characterized. Furthermore the effect of theophylline and 1-n-butyl-3-n-propylxanthine (BPX) on the isolated PDE isoenzymes and on their tracheal relaxant effect were investigated and compared with the nonxanthine PDE inhibitors amrinone and Ro 20-1724. We identified five distinct isoenzymes in guinea-pig tracheal muscle; calcium/calmodulin-stimulated cyclic AMP PDE (PDE I), cyclic GMP-stimulated cyclic AMP PDE (PDE II), cyclic GMP-inhibited and amrinone-sensitive cyclic AMP PDE (PDE III), cyclic AMP-specific and Ro 20-1724-sensitive PDE (PDE IV), and cyclic GMP-specific PDE (PDE V). BPX strongly inhibited the PDE IV isoenzyme with high selectivity, while the inhibitory effect of theophylline was weak. The PDE IV inhibitors BPX and Ro 20-1724 synergistically increased the relaxant effect of the beta 2-adrenoceptor agonist salbutamol in carbachol-contracted trachea much more strongly than theophylline. In contrast, amrinone, a PDE III inhibitor, hardly influenced the relaxant effect of salbutamol, suggesting that the PDE IV isoenzyme is functionally associated with beta 2-adrenoceptors in guinea-pig trachea and that inhibition of this enzyme potentiates the ability of salbutamol to increase the intracellular cyclic AMP content. These results indicate that the PDE IV isoenzyme plays a significant role in alkylxanthine-mediated relaxation of guinea-pig trachea.
Miyamoto
K
K
Research Laboratory for Development of Medicine, Faculty of Pharmaceutical Sciences, Hokuriku University, Kanazawa, Japan.
Kurita
M
M
Sakai
R
R
Sanae
F
F
Wakusawa
S
S
Takagi
K
K
D015105:3',5'-Cyclic-AMP Phosphodiesterases / Q000037:antagonists & inhibitors / Q000302:isolation & purification*; D000318:Adrenergic beta-Agonists / Q000494:pharmacology*; D000420:Albuterol / Q000494:pharmacology; D000818:Animals; D001993:Bronchodilator Agents / Q000494:pharmacology*; D002217:Carbachol; D004357:Drug Synergism; D006168:Guinea Pigs; D007527:Isoenzymes / Q000037:antagonists & inhibitors / Q000302:isolation & purification*; D007700:Kinetics; D008297:Male; D009126:Muscle Relaxation / Q000187:drug effects; D009130:Muscle, Smooth / Q000201:enzymology; D013806:Theophylline / Q000494:pharmacology; D014132:Trachea / Q000201:enzymology*; D014970:Xanthines / Q000494:pharmacology*
C089805:1-n-butyl-3-n-propylxanthine; D000318:Adrenergic beta-Agonists; D001993:Bronchodilator Agents; D007527:Isoenzymes; D014970:Xanthines; D002217:Carbachol; D013806:Theophylline; D015105:3',5'-Cyclic-AMP Phosphodiesterases; D000420:Albuterol