Systemic and topical drug administration in the pig ureter: effect of phosphodiesterase inhibitors alpha1, beta and beta2-adrenergic receptor agonists and antagonists on the frequency and amplitude of ureteral contractions.

PURPOSE: We searched for compounds that are pharmacologically active on ureteral motility for treating ureteral colic to ease retrograde access into the ureter and improve the clearance of stones or stone particles from the ureter. The effects of the alpha1-adrenergic receptor agonist phenylephrine, the nonselective beta and beta2-adrenergic receptor agonists isoproterenol and fenoterol, and the phosphodiesterase inhibitors papaverine (nonspecific) and rolipram (type IV) on the frequency and amplitude of ureteral contractions when administered intravenously or topically were investigated in pigs. MATERIALS AND METHODS: A total of 52 pigs were anesthetized. A double lumen 6Fr catheter was inserted through each renal pelvis and into the ureter, allowing perfusion of saline or drug solution into the renal pelvis and the recording of contractions from the mid portion of the ureter. RESULTS: The alpha1 and beta-adrenergic receptors of the ureter are not tonically activated by endogenous epinephrine or norepinephrine. Phenylephrine administered intravenously at a dose of 0.01 to 3 mg./kg. and topically at 0.1 to 3 mg./ml. per minute increased contraction frequency 10 and 4-fold, respectively, and contraction amplitude 2-fold each in a dose dependent manner. Arterial blood pressure increased markedly during intravenous administration of phenylephrine but was minimally affected during topical application. The phenylephrine effects were reversed by the antagonist prazosin. Isoproterenol administered intravenously at a dose of 0.01 to 10 mg./kg. and topically at 0.1 to 200 microg./ml. per minute decreased contraction frequency to 13% and 31% of controls, respectively. Contraction amplitude was not affected by intravenous administration but decreased to 59% of controls when applied topically. These effects were also observed with a slight delay in the saline perfused contralateral ureter. The heart rate also increased, suggesting absorption of the drug by the urothelium. The isoproterenol effects were blocked by the antagonist propranolol. Fenoterol administered intravenously at a dose of 0.1 to 30 microg./kg. and topically at 0.003 to 1 mg./ml. per minute decreased contraction frequency to 14% and 10% of controls, and contraction amplitude to 84% and 65%, respectively. These effects on the drug perfused ureter were also observed on the contralateral saline perfused ureter but to a lesser extent. The fenoterol effects were blocked by the antagonist propranolol. Papaverine administered intravenously at a dose of 0.001 to 3 mg./kg. decreased contraction frequency to 33% of controls. Topically administered papaverine as well as intravenous and topically administered rolipram had no relevant effect on ureteral motility. CONCLUSIONS: Intravenous phenylephrine increases, and isoproterenol and fenoterol decrease the frequency and amplitude of ureteral contractions in the pig. The same effects are observed with the topical administration of phenylephrine, which causes a significant local but not systemic side effect. Topical administration of isoproterenol and fenoterol produced local as well as systemic effects, suggesting absorption by the urothelium. However, to our knowledge a drug that relaxes ureteral peristalsis in pigs without causing systemic side effects has not yet been identified.