Análise do efeito de inibidores de fosfodiesterase do tipo 5 e agonistas beta adrenergicos em parametros urodinamicos de camundongos utilizando modelo experimental de hiperatividade detrusora

Abstract

Pharmacological treatment of detrusor overactivity (DO) has been classically done with antimuscarinics. Recently new pharmacological agents or association of drugs have been used to treat DO. One of them are the beta3 agonists. Beta 3 agonists increase intracellular cyclic adenosine monophosphate (cAMP) through adenylyl cyclase pathway. cAMP induces detrusor smooth muscle (DSM) relaxation. Phosphodiesterase type 5 inhibitors (PDE-5i) like tadalafil also cause DSM relaxation through nitric oxide/cyclic guanosine monophosphate (NO/cGMP) pathway. Besides the above mechanisms it has been hypothetized that association of beta 3 agonists with PDEi may cause more pronounced DSM relaxation. As a consequence, the principal aim of this in vivo experimental study was to evaluate the impact of association of PDE-5i (tadalafil) and beta3 agonist (BRL 37344) on DO. Thirty mice were randomized into five groups: Control (n=6); L-Ng-Nitroarginine methyl ester hydrochloride (L-NAME) (n=6); L-NAME /tadalafil (n=6); L-NAME / BRL 37344 (n=6); L-NAME/ tadalafil / BRL 37344 (n=6). L-NAME was used to experimentally cause DO on mice by NO deprivation. All animals were submitted to urodynamic studies and the following parameters were evaluated: non-voiding contractions (NVC); frequency of micturition cycles (FM). It was considered as detrusor overactivity the increase in the number of NVC and FM. Comparisons between five groups of treatment were made by analysis of variance (ANOVA) associated with Tukey test. L-NAME Group (4.33 ±2.58) increased the number of NVC compared to Control Group (1,50±0,55). L-NAME/Tadalafil (2.00±1.10), L-NAME/BRL 37344 (1,50±1,52) and L-NAME/Tadalafil/BRL37344 (2,00±1,26 ) Groups decreased number of NVC compared to L-NAME Group (p<0.05). However, co-administration of Tadalafil/BRL 37344 was not more effective than administration of Tadalafil or BRL 37344 alone (Figure 1). L-NAME Group (2,18±0,68) increased the number of FM compared to Control Group (0,69±0,56). L-NAME/Tadalafil (0,97±0,71), L-NAME/BRL 37344 (0,92±0,38) and L-NAME/Tadalafil/BRL 37344 (1,05±0,44) Groups decreased number of FM compared to L-NAME Group (p<0,05). However, co-administration of Tadalafil/BRL 37344 was not more effective than administration of Tadalafil or BRL 37344 alone. Both Tadalafil and BRL 37344 improved DO. Nonetheless, association of tadalafil and BRL 37344 has not an additive effect on DO.