THE EFFECTS OF 2,2-AZOBIS (2-AMIDINOPROPANE) DIHYDROCHLORIDE ON TRACHEAL SMOOTH MUSCLE
Keywords:
Excitation-contraction coupling, 2,2' -azobis (2- amidinopropane) dihydrochloride, smooth muscle, free radicais, peroxyl radical and tracheaAbstract
The effects of 2,2'-Azobis(2-methylpropionamidine) dihydrochloride (AAPH), an inducer agent of free radicais (peroxyl radical) formation, on the rat tracheal smooth muscle. The experiments were performed on tracheal ring preparations maintained in aerated modified Tyrode solution, in pH 7,4 at 37 ºC. The force developed by the tracheal smooth muscle was measured by the isometric force transducer connected to a computerized system. On contractions induced by acetylcholine (10 µM), AAPH presented a biphasic effect: contraction potentiation at low concentration on intact and denuded epithelium preparations (Cfao
= 0,8776 ± 0,415 mM and Cfao = 0,3338 ± 0,343 mM, respectively); and contraction inhibition at high
concentration on intact and denuded epithelium preparations (CE50 = 81,55 62± 4,284 mM and Cfao = 57,7786 ± 8,607 mM, respectively) . On electromechanic coupling, AAPH inhibited contractions induced by KCI (60 mM) on intact and denuded epithelium preparations (CE50 = 57,4037 ± 4,652 mM and Cfao = 32,9650 ± 2,652 mM, respectively) . ln conclusion, AAPH presented a concentration-dependent biphasic effect (pontentiation and inhibition) on pharmacomechanic coupling while it was able to only inhibit the electromechanic coupling. ln conclusion, AAPH presented a concentration-dependent biphasic effect (pontentiation and inhibition) on pharmacomechanic coupling while it was able to only inhibit the electromechanic coupling . Comparing the present data with those available in literature for H202 , we can suggest that these observed effects are not specific for AAPH, but they are derived from the free radicais induced by AAPH.
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