Effects of local anesthetics on the contractility of rat bladders

Purpose: We investigated the effect of local anesthetic agents on the detru sor muscle in rats, Materials and Methods: In vitro isometric contraction of rat detrusor strip s was measured. We investigated the effects of tetracaine, bupivacaine and Lidocaine on baseline spontaneous contractions and contractions induced by various stimuli, including 60 mM. KCl, carbachol and electricalal field sti mulation with a pulse duration of 0.8 or 100 milliseconds. Results: Local anesthetic agents have complex effects on baseline spontaneo us contractility that depend on the type of agent used and its concentratio n. These agents inhibited nerve mediated contraction resulting from electri calal field stimulation with a pulse duration of 0.8 milliseconds in a conc entration dependent manner and also inhibited nonnerve mediated detrusor co ntractions induced by KCI, carbachol or electricalal field stimulation with a pulse duration of 100 milliseconds Higher concentrations of local anesth etic agents were needed to inhibit nonnerve than nerve mediated contraction s. In rat detrusor muscle carbachol induced a sustained tonic contraction e ven after the depletion of internal and external Ca2+ sources, which was al so inhibited by local anesthetic agents. Conclusions: These results show that local anesthetic agents have a wide sp ectrum of inhibitory effects on the contraction of bladder smooth muscle in duced by various stimulants at different concentrations, which may be poten tially useful for treating overactive bladder.