[Pharmacological analysis of neurotransmitters contributing to lower urinary tract function]

Lower urinary tract function is controlled by the autonomic nervous system, which consists of adrenergic, cholinergic, and non-adrenergic, non-cholinergic (NANC) neurons. We have measured the amount of various neurotransmitters (acetylcholine, ACh; noradrenaline, NA; adenosine triphosphate, ATP; and nitric oxide, NO) released from human and rabbit urinary tract smooth muscles by the microdialysis method coupled with HPLC. Muscle strips are isolated from human or rabbit bladder, urethra, and prostate. A microdialysis probe was inserted into each smooth muscle strip. Each muscle strip was connected to an isometric transducer, and tension development was measured. We have evaluated the changes in electrical field stimulation-induced neurotransmitter releases and functional responses in physiological and pathological conditions and the interactions between neurotransmitters or neurons. In this review, we present several of our results: 1) interactions between adrenergic and nitrergic neurons in rabbit urethra, 2) effect of NO on human bladder function, 3) effect of NO on human prostate function, and 4) effects of aging on acetylcholine and ATP releases from human bladder smooth muscles. These data may reveal physiological or pathological neurotransmitter control of lower urinary tract function and give us useful information for clinical intervention to treat lower urinary tract symptoms.