Evidence for beta(3)-adrenoceptor subtypes in relaxation of the human urinary bladder detrusor: Analysis by molecular biological and pharmacological methods

The purpose of the present study was to confirm the presence of beta(3)-adr enoceptor subtype in the relaxation of human urinary bladder detrusor tissu e by reverse transcription-polymerase chain reaction (PCR); direct sequenci ng of the PCR product, in situ hybridization; and isometric contraction. Us ing reverse transcription-PCR, the mRNAs of three receptor subtypes (beta(1 ), beta(2), and beta(3)) were expressed in the human urinary bladder detrus or tissue. Direct sequencing of the PCR product of the above beta(3)-adreno ceptor revealed no mutation in the amplified regions. In situ hybridization with digoxygenin-labeled oligonucleotide probe revealed the presence of th e mRNA of beta(3)-adrenoceptor subtype in the smooth muscle of the urinary bladder. The relaxant effects of isoproterenol (a nonselective beta-adrenoc eptor agonist); ZD7114, BRL37344, and CGP12177A (putative selective beta(3) -adrenoceptor agonists); and SR59230A (a putative selective beta(3)-adrenoc eptor antagonist) were tested using an isometric contraction technique. Iso proterenol in either the presence or absence of both atenolol (a beta(2)-ad renoceptor-selective antagonist) and butoxamine (a beta(2)-adrenoceptor-sel ective antagonist) revealed a relaxant effect on the carbachol-induced cont raction of the human urinary bladder detrusor. Both BRL37344 and CGP12177A also revealed relaxant effects on the human urinary bladder detrusor, but Z D7114 did not elicit any relaxation. These results suggest that beta(3)-adr enoceptor may have some role in urine storage in the human urinary bladder.