Effect of chloroquine on the contractility of the smooth muscles of the rat uterus, trachea and urinary bladder.

This study was performed to investigate the effect of chloroquine (CQ) on the contractility of isolated smooth muscles of the rat uterus, urinary bladder; and trachea. Chloroquine, 4 x 10(-4) mol.l-1 completely abolished uterine contractions produced by 10(-2) IU/ml oxytocin, and 10(-6) mol.l-1 5-hydroxytryptamine (5-HT) and acetylcholine (Ach). Chloroquine also caused a concentration-dependent relaxation of 10(-6) mol.l-1 Ach-contracted rat trachea. Cumulative addition of CQ (10(-8)-10(-3) mol.l-1) to spontaneously contracting rat urinary bladder did not produce any significant effect. It also did not affect the contractile response of the bladder to Ach and 5-HT. The results suggest that CQ inhibits the contractile process in the rat uterus and trachea but not the urinary bladder.