COMPARISON OF DETRUSOR CONTRACTILITY OF GUINEA-PIG BLADDERS IN-SITU AND STRIPS FROM THESE IN-VITRO

To study the relative importance of neurogenic factors in detrusor con tractility, active bladder wall stress values were compared in situ an d in vitro. Eight male guinea pigs were used. The active stress in the bladder wall in spontaneous micturition contractions was calculated f rom the results of urodynamic examinations and compared with the activ e stress developed in response to optimum electrical stimulation in fu ll-thickness bladder wall strips taken from the same bladders. The res ults indicated that, in normal micturition, the detrusor muscle is not fully stimulated, and the rate of pressure development is not determi ned by mechanical factors. To identify topological variations of detru sor contractility, the strips were taken from three different location s. It was found that strips from the posterior wall contracted more fo rcefully than those from the anterior wall.