Effect of alpha 1-adrenoceptor antagonists on urinary bladder function in urethane-anesthetized rats.
1. We investigated the effects of selective alpha 1-adrenoceptor antagonists on rhythmic bladder contraction and cystometrograms as representative of urinary bladder function in urethane-anesthetized rats. 2. The selective alpha 1-adrenoceptor antagonists tamsulosin (0.03-3 micrograms/kg IV), prazosin (0.03-3 micrograms/ kg IV) and bunazosin (0.03-3 micrograms/kg IV) exerted little effect on the amplitude and frequency of rhythmic bladder contraction in anesthetized rats. In contrast, the antipollakiuria agent flavoxate (5 and 10 mg/kg IV) induced a dose-dependent disappearance in frequency without affecting the amplitude of the contractions. 3. Tamsulosin (1 and 3 micrograms/kg IV), prazosin (1 and 3 micrograms/kg IV), and bunazosin (1 and 3 micrograms/kg IV) exerted no effect on the cystometrogram, either. However, flavoxate (5 and 10 mg/kg IV) raised the micturition threshold pressure and prolonged the time to micturition. 4. These results suggest that the alpha 1-adrenoceptor plays little role in urinary bladder contraction in anesthetized rats.
Sudoh
K
K
Cardiovascular Research Laboratories, Yamanouchi Pharmaceutical, Ibaraki, Japan. sudoh@yamanouchi.co.jp
Inagaki
O
O
Takenaka
T
T
D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology*; D000777:Anesthetics / Q000494:pharmacology; D000818:Animals; D005422:Flavoxate / Q000494:pharmacology*; D008297:Male; D010276:Parasympatholytics / Q000494:pharmacology*; D011224:Prazosin / Q000494:pharmacology; D011799:Quinazolines / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D013449:Sulfonamides / Q000494:pharmacology; D000077409:Tamsulosin; D014520:Urethane / Q000494:pharmacology*; D001743:Urinary Bladder / Q000187:drug effects* / Q000502:physiology
D000317:Adrenergic alpha-Antagonists; D000777:Anesthetics; D010276:Parasympatholytics; D011799:Quinazolines; D013449:Sulfonamides; D005422:Flavoxate; D014520:Urethane; C018176:bunazosin; D000077409:Tamsulosin; D011224:Prazosin