암컷백서 요도내압에 대한 선택적 알파아드레날린수용체 차단제의 이완 반응
(The) Effects of α1A Adrenoceptor Inhibitors on the Urethral Perfusion Pressure of Female Rat
암컷백서 요도내압 알파아드레날린수용체;
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Aims of Study: α1A-adrenoceptor antagonist may play an important role in the treatment of functional bladder outlet obstruction(BOO) in female. However detailed examinations of in vivo study have rarely been reported. This study was performed to identify the effects of α1A-adrenoceptor antagonist on the urethral perfusion pressure(UPP) and also to assess its therapeutic potentials for female BOO. Materials and Methods: Under urethane anesthesia(20%, 0.5ml/100gm, I.P.), a cannula(PE-50) was placed in the femoral artery for drug administration and systemic blood pressure monitoring in each animal. Bladder and proximal urethra were exposed through a midline abdominal incision. UPP and vesical pressure(Pves) were monitored using a triple-lumen catheter, which was introduced transvesically through a separate incision in the bladder dome and located securely in the bladder neck. Tamsulosin(group Ⅰ), doxazosin(group Ⅱ) and phentolamin(group Ⅲ) were injected in female rat via femoral cannula. Tamsulosin was also injected to male rat(group Ⅳ) for being compared with Group Ⅰ. Results: After administration of 0.1ml tamsulosin (10^(-7) M) in female rat(group Ⅰ), frequency was significantly decreased from 0.44±0.23 to 0.32±0.18 and the duration of minimal urethral relaxation with high frequency oscillations(Dhfo) was significantly prolonged from 33±6 to 44±8. All the parameters were not significant different compared with the other female rat groups(group Ⅱ and group Ⅲ) except mean arterial blood pressure. The changes of mean arterial pressure after tamsulosin(-1.5±0.4 mmHg) were significantly lower than those after doxazosin(-9.6±3.9 mmHg) and phentolamin(-13.5±4.9 mmHg). In male rat (group Ⅳ), before administration of tamsulosin, UPP, and Pves curves were similar to those of female rat. However, maximal Pves was significantly higher than group Ⅰ. After adminstration of tamsulosin in group Ⅳ, the prolongation of frequency and Dhfo were significant compared with group Ⅰ. Conclusions: In female rat urethra, α1A adrenoceptor may be functional subtype. α1A-adrenoceptor antagonist prolonged the duration of high frequency oscillation and decrease frequency of involuntary bladder contraction. It might be possible that α1A-adrenoceptor antagonist improves not only obstructive symptoms but also bladder irritative symptoms, by prolonging the duration of high frequency oscillation and frequency of involuntary bladder contraction.