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J Urol. 1998 Jun;159(6):2197-201.

Expression of beta3-adrenoceptors in rat detrusor smooth muscle.

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  • 1Division of Molecular Cardiology, Research Institute of Angiocardiology, Faculty of Medicine, Kyushu University, Fukuoka, Japan.

Abstract

PURPOSE:

To investigate the expression of beta-adrenoceptor (AR) subtypes responsible for detrusor smooth muscle relaxation.

MATERIALS AND METHODS:

Isolated rat detrusor smooth muscle was examined by tension measurement and reverse transcription polymerase chain reaction (RT-PCR).

RESULTS:

Norepinephrine (NE), epinephrine (EP) and isoproterenol (ISO) were found to relax the detrusor muscle pre-contracted by 6 x 10(-7) M carbachol in the presence of 10(-6) M phentolamine. NE relaxed the detrusor muscle as potently as EP. This potency order (NE=EP) thus indicated the beta-ARs of the rat detrusor muscle to possibly be a beta1 subtype. However, in the presence of 10(-6) M propranolol, beta1- and beta2- but not beta3-AR antagonist, NE showed a more potent relaxation than EP. This observation indicated that the rat detrusor muscle also possesses beta3-AR. RT-PCR revealed all three subtypes of beta-AR mRNA, namely beta1-, beta2- and beta3-AR mRNA, to be expressed in rat detrusor smooth muscle cells.

CONCLUSION:

We concluded that beta3-ARs exist in rat detrusor smooth muscle based on both pharmacological and molecular biological studies. Based on these findings, beta-ARs of rat detrusor smooth muscle are considered to be mixed populations consisting of three subtypes which play an important role in relaxing smooth muscle in response to catecholamines.

PMID:
9598569
[PubMed - indexed for MEDLINE]
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