In vitro reactivity of urinary bladder smooth muscle in rabbits influenced by xanthine derivatives

The contractions of urinary bladder smooth muscle are evoked by parasympathetic nervous system, with its main mediator acetylcholine. These contractions can be inhibited by two basic mechanisms--inhibition of contraction (anticholinergic drugs) or inducing the relaxation (sympathomimetics, calcium channel blockers). In this study, we investigated the effect of caffeine and theophylline--both are nonselective inhibitors of phosphodiesterase--on urinary bladder smooth muscle contractions evoked by acetylcholine. The reactivity of the urinary bladder smooth muscle was estimated by in vitro method using organ chambers. Caffeine and theophylline caused decrease of urinary bladder smooth muscle reactivity to acetylcholine. This decrease was statistically significant only in concentrations of 10(-4) and 10(-3) mol.l(-1) of caffeine and theophylline. Caffeine and theophylline significantly influenced the reactivity of urinary bladder smooth muscle in guinea pigs to acetylcholine. By comparing the influence of aminophylline we can conclude, that caffeine as well as theophylline caused significantly stronger decrease of the reactivity to acetylcholine than aminophylline only in lower concentration (Fig. 4, Ref. 30). Full Text (Free, PDF) www.bmj.sk.