Contractile responses and calcium mobilization induced by muscarinic agonists in the rat urinary bladder: Effects of age

In the current study, the contractile responses to muscarinic stimulation of urinary bladder strips from young rats and aged rats were compared. 1. The EC(50) values of the two groups in response to bethanechol were similar. 2. The magnitude and the velocity of tension generation was significantly lower in strips from the aged group. 3. The magnitude as well as the velocity of tension generation in response to high K+ solution of the two models were similar. 4. The time to peak [Ca2+](i) in response to bethanechol was prolonged in strips from the aged group as compared with the young group. 5. Ca-45(2+) influx in response to bethanechol was significantly reduced in the aged group as compared with the young group. It is concluded that the reduced contractile response to muscarinic stimulation of isolated urinary bladder strips from aged rats is mediated at least in part by a decreased rate of Ca2+ entry. (C) 1997 Elsevier Science Inc.