Objectives To investigate the receptors for angiotensin II (AII, reported to be a potent contractile agent in human urinary bladder), using functional and autoradiographic techniques in child and adult bladder specimens. Materials and methods Bladder specimens were obtained from 61 children (aged 4 months to 12 years) undergoing ureteric reimplantation for vesico-ureteric re¯ux, and from 10 adults undergoing cystectomy. After overnight storage, the mucosa was removed and isometric contractions obtained from detrusor muscle strips in the presence of phosphoramidon (10 mmol/ L). Only one concentration of AII was added to each preparation because of tachyphylaxis.
Objective To investigate whether a history of recurrent urinary tract infection (UTI) and/or the presence of day-wetting/urge symptoms might in¯uence the contractile responses to the cholinergic agonist carbachol or to the sensory neuropeptide neurokinin A (NKA) in the urinary bladder in children. Patients and methods Small detrusor strips were taken from the margin of the cystotomy incision of the bladder dome during surgery to correct vesico-ureteric re¯ux (VUR) in 62 children (aged 4 months to 12 years) or for unrelated bladder conditions in ®ve controls (aged 3 months to 13 years). Concentrationresponse curves to carbachol and NKA were constructed using organ-bath techniques, and results compared for age, sex, weight of the detrusor strip, UTI history or day-wetting syndrome. Results The contractile responses to NKA were no different for any of the features investigated. The contractile response to carbachol and NKA in detrusor from control and VUR patients was not signi®cantly different. The children with a history of UTI were signi®cantly older than those without. The contractility in response to carbachol was greater in older girls (aged 4±12 years) than younger girls (<4 years) and than in all boys (<4 years and 4±12 years; ANOVA P = 0.013). The mean (SEM) maximum contractile response to carbachol in the group of 20 young children (4±30 months) with previous UTI was 3.0 (0.3) g, whereas the maximum response in the age-matched group of 11 without UTI was 1.8 (0.3) g (P = 0.046). There were no signi®cant differences in maximum responses between those with day-wetting and those without (aged >4 years), although there was a signi®cant difference in pD 2 value, at 6.19 (0.13) and 5.58 (0.14), respectively (P = 0.018). Conclusion Carbachol produced a larger contractile response in detrusor from children with a history of UTI than from those without, indicating possible alterations in muscarinic receptor characteristics. An increased sensitivity to muscarinic stimulation in daywetting children was also suggested, whereas NKA is unlikely to be involved in any of these pathophysiological conditions.
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