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Urothelial beta‐3 adrenergic receptors in the rat bladder
Author(s) -
Kullmann F. Aura,
Downs Thomas R.,
Artim Debra E.,
Limberg Brian J.,
Shah Mansi,
Contract Dan,
de Groat William C.,
Rosenbaum Jan S.
Publication year - 2011
Publication title -
neurourology and urodynamics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.918
H-Index - 90
eISSN - 1520-6777
pISSN - 0733-2467
DOI - 10.1002/nau.20965
Subject(s) - urothelium , cystometry , detrusor muscle , medicine , overactive bladder , urinary bladder , agonist , reflex , immunostaining , endocrinology , receptor , urology , smooth muscle tissue , pathology , immunohistochemistry , smooth muscle , alternative medicine
Aims To investigate the distribution of beta‐3 adrenergic receptors (β 3 ARs) in the rat bladder and to examine the contribution of urothelial β 3 ARs to agonist‐induced suppression of bladder reflexes and relaxation of smooth muscle. Methods Bladder tissue was collected from 8‐ to 10‐month old female SD rats. In some samples, the urothelium was surgically separated from the smooth muscle. The expression and localization of βAR mRNA and β 3 AR protein were determined using RT‐PCR and immmunohistochemistry. Contractile responses to the specific β 3 AR agonists TAK‐677 and BRL37344 were measured in bladder strips with or without the urothelium. The contribution of urothelial β 3 ARs to the micturition reflex was assessed in continuous cystometry in urethane anesthetized rats using intravesical delivery of β 3 AR agonists. Results RT‐PCR detected mRNA of all βARs in urothelium and smooth muscle. Immunostaining detected β 3 ARs throughout the urothelium, in the smooth muscle, myofibroblast‐like cells, and in the peripheral nerves. Ovariectomy did not change the distribution of β 3 ARs in any bladder structure. Intravesical administration of TAK‐677 and BRL37344 (1–5 × 10 −4 M) decreased voiding frequency and amplitude of bladder contractions. In bladder strips in vitro both β 3 AR agonists (10 −12 to 10 −4 M) relaxed the smooth muscle in a concentration‐dependent manner to the same extent in strips with and without the urothelium. Conclusions In addition to their presence in bladder smooth muscle, β 3 ARs are present in the urothelium where their activation may alter reflex voiding via release of factor(s) that act on non‐myocyte structures including the afferent and/or efferent nerves to influence bladder contractility. Neurourol. Urodynam. 30:144–150, 2011. © 2010 Wiley‐Liss, Inc.