Expression of β ‐Adrenoceptor Subtypes in Urothelium, Interstitial Cells and Detrusor of the Human Urinary Bladder

Objective: We examined whether interstitial cells (ICs) of the human urinary bladder expressed β ‐adrenoceptor (AR) subtypes, and semiquantitatively compared the staining intensity among urothelium, ICs and detrusor muscles. Methods: Paraffin sections of the human urinary bladder were obtained from histologically normal areas of formalin‐fixed specimens removed for bladder carcinoma. Double‐labeling immunohistochemical methods using antibodies against each β ‐AR subtype and vimentin were performed to identify ICs of the human urinary bladder. The staining intensity of β ‐ARs was semiquantitatively compared among urothelium, ICs and detrusor muscles. Further, gender‐related difference or age‐related correlation in the staining intensity of β ‐ARs was compared in the same cell types. Results: The expression of β 1 ‐, β 2 ‐, and β 3 ‐AR was observed in vimentin‐positive ICs localized in suburothelium, between detrusor muscle bundles, and within these bundles of the human urinary bladder. The rank order of the staining intensity was urothelium > ICs = detrusor muscles in β 1 ‐AR, urothelium > ICs > detrusor muscles in β 2 ‐AR, whereas its order was ICs = detrusor muscles > urothelium in β 3 ‐AR. Except for urothelial β 1 ‐AR, there was no gender‐related difference in the signal intensity of β ‐ARs in the urothelium, ICs or detrusor muscles. Age negatively correlated with the signal intensity of all β ‐AR subtypes. Conclusion: β ‐ARs were expressed in vimentin‐positive ICs of the human urinary bladder. As for β 2 ‐ and β 3 ‐AR, there was no gender‐related difference or age‐related correlation in urothelium, ICs and detrusor muscles. In the human urinary bladder, β ‐ARs expressed in ICs may play a role in bladder physiology.