Effects of isoproterenol and butylscopolamine on the friction between an artificial stone and the intraureteral wall in anesthetized rabbits

Purpose: We evaluated the effects of the nonselective beta -adrenoceptor agonist isoproterenol and the nonselective muscarinic antagonist butylscopolamine on ureteral wall tension, namely friction between an artificial stone and the intraureteral wall, in anesthetized rabbits. Materials and Methods: The relaxing effect of the drugs on the KCl induced tonic contraction was examined in isolated rabbit ureters. The effect of the drugs on the applied force needed for the artificial stone to pass at a constant speed through the ureter, called sliding force, was evaluated in anesthetized rabbits. Results: In a concentration dependent manner isoproterenol but not butylscopolamine reduced the KCl induced contraction in isolated ureter (mean pD(2) 7.35 +/- 0.06). Intravenous administration of 1 and 10 mug/kg. isoproterenol significantly decreased the friction between the artificial stone and intraureteral wall in anesthetized rabbits with sliding force at 15 minutes after drug administration decreased by 54.5% and 63.6%, respectively. In contrast, 100 and 1,000 mug./kg. butylscopolamine intravenously had no evident effect on ureteral wall tension. Conclusions: Our results strongly suggest that ureteral smooth muscle relaxation by,B-adrenergic stimulation reduces ureteral wall tension, thereby, diminishing mechanical effects impeding the movement of a ureteral stone down the ureter.