1997 Fiscal Year Final Research Report Summary
Research of adrenoceptorsin the proximal urethral smooth muscle
| Project/Area Number |
07671740
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Urology
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| Research Institution | Kyushu University (1997)
宮崎医科大学 (1995-1996) |
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Principal Investigator |
YAMAGUCHI Takanori Kyushu Univrsity, Asistant Prof., 医学部, 講師 (20182446)
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| Co-Investigator(Kenkyū-buntansha) |
NAGANO Masashi Miyazaki Medical College Research Associate, 助手 (90295220)
ITOI Tatsunori Miyazaki Medical College Research Associate, 助手 (10244203)
NAGATA Toyoharu Miyazaki Medical College Research Associate, 助手 (60218005)
KITADA Shinichiro Miyazaki Medical College Associate Professor, 助教授 (20128375)
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| Project Period (FY) |
1995 – 1997
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| Keywords | proximal urethra / adrenoceptor / isovolumetric urethral pressure study / isometric muscle strips study / alpha-1 and alpha-2 agonist / alpha-1 blockers |
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| Research Abstract |
The role of alpha-1 and alpha-2 adrenoceptors in the contractile response of proximal urethra to agonists and antagonists was studies in female and male rabbits. We performed thein vivo and in vitro isovolumetric urethral pressure study and isometric study. The response pattern for alpha-1 agonists showed a sharp rise, while that for alpha-2 agonists showed a gradual increase to a amaximum pressure. The duration of the response of alpha-2 agonists was significantly longer than that of alpha-1 agonists. A difference in the response between alpha-1 and alpha-2 would be produced mainly through different receptor functions. The magnitude of the response of alpha-1 adrenoceptors in the male rabbits was almost twice that of the female rabbits. Our experimental findings indicate that alpha-2 stimulation mediates a slow and prolonged response that is essential for urinary continencein female rabbits.
We evaluated the effects of alpha-1 blockers on rabbit urethra and cardiovascular synstem comparatively in an in vivo isovolumetric urethral pressure model. Prazosin and bunazosin were proved to be more potentto both urethra and vascular synstems. However, tamsulosin and alfuzosin displayd a marked blockage to the phenylephrine-induced increase in urethral pressure without so moch blockage in arterial pressure. Tamsulosin seemed to be a most effective alpha-1 blocker for relieving proximal urethral contraction with mild effects on blood pressure among the drugs in the present study.
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