[Effect of moxisylyte on the lower urinary tracts (1). Effect on the isolated rabbit urethra and bladder].
Effect of moxisylyte on the lower urinary tracts was studied in comparison with those of prazosin and bunazosin in the isolated rabbit bladder and urethra. Moxisylyte dose-dependently inhibited the urethral contraction induced by phenylephrine. The IC50 value of moxisylyte was 1.01 x 10(-6) M. Prazosin and bunazosin inhibited the urethral contraction as well as moxisylyte. The IC50 values of prazosin and bunazosin were 2.88 x 10(-7) M and 1.44 x 10(-7) M, respectively. Moreover, moxisylyte and bunazosin inhibited the urethral contraction induced by KCl. The IC50 values of moxisylyte and bunazosin were 1.17 x 10(-5) M and 1.35 x 10(-4) M, respectively. The KCl/phenylephrine ratios of moxisylyte, bunazosin and prazosin were as follows: 17, 938 and 9201, respectively. Moxisylyte has a relaxant action on the urethra that is probably ascribable to its alpha 1-adrenoceptor antagonist and Ca++ antagonist actions. In the isolated bladder, moxisylyte inhibited the bladder contraction induced by KCl, with an IC50 value of 4.46 x 10(-5) M. However, moxisylyte did not affect the contractile response to acetylcholine. These results suggest that the relaxant effect of moxisylyte on the urethra is due to alpha 1-adrenoceptor antagonist and Ca++ antagonist actions. Therefore, moxisylyte is useful for the therapeutic treatment of micturitional disorder.
Watanabe
K
K
Pharmaceuticals Research Laboratories, Fujirebio Inc., Tokyo, Japan.
Hayashi
Y
Y
Ikeda
K
K
Ohnishi
H
H
D000317:Adrenergic alpha-Antagonists; D000818:Animals; D002121:Calcium Channel Blockers; D004305:Dose-Response Relationship, Drug; D066298:In Vitro Techniques; D008297:Male; D013948:Moxisylyte / Q000494:pharmacology*; D009119:Muscle Contraction / Q000187:drug effects*; D009130:Muscle, Smooth / Q000187:drug effects; D010656:Phenylephrine / Q000037:antagonists & inhibitors; D011189:Potassium Chloride / Q000037:antagonists & inhibitors; D011224:Prazosin / Q000494:pharmacology; D011799:Quinazolines / Q000494:pharmacology; D011817:Rabbits; D014521:Urethra / Q000187:drug effects*; D001743:Urinary Bladder / Q000187:drug effects*
D000317:Adrenergic alpha-Antagonists; D002121:Calcium Channel Blockers; D011799:Quinazolines; D010656:Phenylephrine; D011189:Potassium Chloride; C018176:bunazosin; D013948:Moxisylyte; D011224:Prazosin