[Pharmacological experiments in aged rat urinary bladder. II. Responses to ATP, prostaglandin F2 alpha, serotonin, angiotensin II and VIP].

To investigate the possible etiology of unstable bladder in the elderly, we investigated the responses of the aged rat bladder (16 and 24 months old) to 5 non-cholinergic, non-adrenergic neurotransmitters in comparison with the young rat bladder (6 months old). The drugs used were adenosine triphosphate, prostaglandin F2 alpha, serotonin, angiotensin II and vasoactive intestinal polypeptide. 1) The responses of 24-month-old rat bladders to adenosine triphosphate (ATP) were significantly greater than those of 6- and 16-month-old rats. 2) Prostaglandin F2 alpha made no difference in responses among three age groups. 3) The responses to serotonin of 24-month-old rat bladders were greater than those of the other two groups. 4) There was no difference in responses to angiotensin II in three age groups. 5) No response to vasoactive intestinal polypeptide was observed in all age groups. It is probable that the supersensitive responses to ATP and serotonin, observed in the aged rat bladders, may contribute to the development of unstable bladder in elderly people.