[Pharmacological experiments in aged rat urinary bladder. I. The responses to acetylcholine, norepinephrine and...

To investigate the etiology of unstable bladder in elderly people, we performed pharmacological experiments using the body of the rat urinary bladder. Responses to acetylcholine, norepinephrine and isoproterenol were examined in vitro in aged rats (16 and 24 months old) in comparison with young rats (6 months old). The results of the present study were summarized as follow: 1) The body weight of 16 and 24 months rats was significantly greater than that of the control. 2) There was no significant difference in the response to acetylcholine among three age groups. 3) The contraction strength of 16- and 24-month-old rat urinary bladder induced by norepinephrine was significantly greater than that of the control. 4) The relaxation response of the detrusor strips induced by isoproterenol in 24-month-old rats was significantly smaller than that of the other two groups. It is concluded that responses to alpha-adrenergic agonists were enhanced in the aged rat urinary bladders. In the assumption that a similar change occurs in the human bladders, the age-related increase in the responsiveness to alpha-adrenergic agonists is one of the etiologies or contributing factors for unstable bladder.