Mechanical Function and Gene Expression of α1 -Adrenoceptor Subtypes in Dog Intravesical Ureter

• Published in: Urology (Ridgewood, N.J.) N.J.), 2009-08, Vol.74 (2), p.458-462
• Main Authors: Kobayashi, Shinya, Tomiyama, Yoshitaka, Hoyano, Yuji, Yamazaki, Yoshinobu, Kusama, Hiroshi, Kubota, Yasue, Sasaki, Shoichi, Kohri, Kenjiro
• Format: Article
• Language: English
• Subjects: Biological and medical sciences; Medical sciences; Nephrology. Urinary tract diseases; Urology
• ISSN: 0090-4295; 1527-9995
• DOI: 10.1016/j.urology.2009.01.009

Objectives To characterize the contractile functions and gene expression of the α1 -adrenoceptor (AR) subtypes present in the dog intravesical ureter. Methods In a functional study, α1 -AR antagonists were evaluated against phenylephrine (α1 -AR agonist)-induced contractions in dog isolated intravesical ureteral preparations. The quantitative expression of α1 -AR subtype mRNA in this tissue was determined using real-time quantitative reverse transcriptase-polymerase chain reaction. Results In the isolated intravesical ureter, prazosin (nonselective α1 -AR antagonist), silodosin (selective α1A -AR antagonist), naftopidil (selective α1D -AR antagonist), and BMY-7378 (selective α1D -AR antagonist) all shifted the concentration-contractile response curve for phenylephrine to the right. The rank order of potencies (p KB value) was silodosin (9.45 ± 0.14), prazosin (8.16 ± 0.08), naftopidil (7.39 ± 0.19), and BMY-7378 (6.78 ± 0.20). The α1A -AR antagonist silodosin was much more potent than the 2 α1D -AR antagonists. The rank order of mRNA expression levels among the α1 -AR subtypes was α1d (72.68%), α1a (24.14%), and α1b (3.18%). Conclusions In the dog intravesical ureter, α1A -AR plays a major role in contraction, despite the prevalence of α1D -AR.