Effects of local anesthetics on human bladder contractility

AIMS: We investigated the invitro effects of local anesthetics on the contractility of the human bladder. METHODS: By measuring the invitro isometric contractions of human bladder strips, we determined the effects of tetracaine, bupivacaine, lidocaine, and ropivacaine on the basal spontaneous contractions and contractions induced by various stimuli, namely, KCl (60 mM), carbachol (CCh), and electrical field stimulation (EFS). The effect of local anesthetic agents on Ca(2+)-independent sustained tonic contraction (SuTC) of the detrusor was also investigated. RESULTS: Local anesthetics increased phasic and tonic spontaneous contractile activity dose dependently in the concentration range 1-500 muM, but abolished phasic activity at higher concentrations. Local anesthetic agents inhibited nerve-mediated contraction (EFS, 0.8 msec) in a concentration-dependent manner (ropivacaine > tetracaine = bupivacaine > lidocaine), and inhibited non-nerve mediated contractions induced by KCl, long pulse EFS (direct muscle stimulation, 100 msec), and CCh. Inhibitory potency on non-nerve mediated contraction was for long pulse EFS: ropivacaine = tetracaine > bupivacaine = lidocaine and for KCl- and CCh-induced contractions: ropivacaine > tetracaine > bupivacaine = lidocaine. Higher concentrations of local anesthetics were needed to inhibit non-nerve-mediated bladder contraction than nerve-mediated contraction. SuTC was suppressed by all local anesthetics concentration dependently. CONCLUSIONS: Our study demonstrates that local anesthetics have inhibitory effects on the contraction of human bladder as induced by different stimulants and concentrations. Their effects and differences suggest that they may be considered potentially useful as diagnostic and therapeutic agents for bladder dysfunction.