Purinergic and cholinergic contractions in adult and neonatal rabbit bladder

The contractile responses of isolated strips, of urinary bladder smooth muscle to various agonists and to nerve stimulation were compared in tissues taken from adult (greater than 14 weeks old) and neonatal (less than 1 week old) rabbits. There was no significant difference in the sensitivity of adult and neonatal tissues to a range of concentrations of acetylcholine (ACh) or carbachol, but in the neonatal tissues the contractile responses to ATP and to alpha, beta-methylene-ATP were significantly greater than in tissues from the adult. The contractile response to nerve stimulation was significantly greater in the neonatal tissues than in the adult. Experiments examining neurogenic contractions after atropine or desensitization of P2x purinoceptors suggest that the contribution of ATP and ACh to the contractile response changes with ageing.