['Testosterone treatment of rats produces prostatic hypertrophy and detrusor overactivity. Whether or not the detrusor overactivity can be related to an increase in the responsiveness of lower urinary tract smooth muscles is not known.', 'Male Sprague-Dawley rats were given daily injections of testosterone propionate for 2 weeks. Effects on cystometric parameters and on the responsiveness of isolated detrusor, urethral, and prostate smooth muscle preparations to drugs and electrical field stimulation were investigated.', 'Testosterone treatment increased prostatic weight twofold (controls, 768 mg; testosterone-treated, 1,478 mg), but not bladder weight (103 mg vs. 116 mg). Micturition pressure (77%), bladder capacity (75%), residual volume (56%), and micturition volume (83%) increased significantly in treated animals, and bladder overactivity developed. No effect of intraarterial doxazosin on these changes was observed. The differences in urodynamic parameters between control and testosterone-treated rats could not be correlated with changes in bladder, urethral, or prostate excitatory innervation, as revealed by responses to electrical field stimulation, or by smooth muscle responses to different contractant drugs.'] Does testosterone-induced prostatic growth in the rat cause bladder overactivity unrelated to detrusor hypertrophy?