Adenylate cyclase and phosphodiesterase activity in rabbit ureter

Adenylate cyclase and phosphodiesterase enzyme activities were demonstrated in rabbit ureter. NaF, 10 mM, caused a 60.9 per cent increase in adenylate cyclase activity. Isoproterenol, 5 X 10-7 to 10-5 M induced a statistically significant dose-dependent increase in adenylate cyclase activity which was suppressed by propranolol, 10-7 M. Theophylline, 5 X 10-5 to 10-2 M, significantly inhibited phosphodiesterase activity. Thus, isoproterenol and theophylline, two agents that can relax ureteral segments previously contracted by a depolarizing concentration of potassium, could presumably increase cyclic AMP levels, isoproterenol by increasing synthesis and theophylline by decreasing degradation.