Quantitative analysis of the levels of expression of muscarinic receptor subtype RNA in the detrusor muscle of patients with overactive bladder.

Abstract

Antimuscarinic drugs have frequently been used for the treatment for patients with an overactive bladder (OAB) and there have been many studies on the distribution of muscarinic receptor subtypes in the bladder. However, the distribution of muscarinic receptor subtypes in OAB patients has not been well investigated. In this study we investigated the distribution of muscarinic receptor subtypes with mRNA and protein expressions in patients with and without OAB, and investigated both the dome and trigone area. Samples of bladder smooth muscle were obtained from 10 individuals, five patients with OAB and a non-OAB group consisting of five patients who received radical cystectomy. The M2 receptor was predominant, but there was no significant difference in the level of M2 expression between the groups in the dome area. M5 expression in the dome area was significantly higher in the OAB group than in the non-OAB group. In the trigone area, the level of M2 mRNA expression was the highest in the non-OAB group, and was significantly lower in the OAB group. The levels of M1 and M5 mRNA expression were also observed in samples obtained from the trigone area. The multiformity of the muscarinic receptor subtypes in human bladder smooth muscle was confirmed, and our results suggest that the efficacy of a given pharmacologic therapy differs from patient to patient.