Piboserod (SB 207266), a selective 5-HT4 receptor antagonist, reduces serotonin potentiation of neurally-mediated contractile responses of human detrusor muscle.
The aim of this study is to evaluate the potency of piboserod (SB 207266), a selective 5-HT(4) receptor antagonist, at inhibiting the 5-HT(4)-mediated potentiating effect of serotonin (5-HT) on the neurally-mediated contractile responses of human detrusor strips to electrical field stimulations (EFS). Strips of human detrusor muscle were mounted in Krebs-HEPES buffer under a resting tension of 500 mg and EFS (20 Hz, 1 ms duration at 300 mA for 5 s) was applied continuously at 1 min intervals. After stabilization of the EFS-induced contractions, concentration-response curves to 5-HT (0.1 nM-100 microM) were constructed in the absence or presence of 1 or 100 nM of piboserod. The experiments were performed in the presence of methysergide (1 microM) and ondansetron (3 microM) to block 5HT(1)/5HT(2) and 5-HT(3) receptors, respectively. 5-HT potentiated the contractile responses to EFS of human bladder strips in a concentration-dependent manner, with a maximum mean of 60.0+/-19.9% of the basal EFS-evoked contractions. Piboserod did not modify the basal contractions but concentration-dependently antagonized the ability of 5-HT to enhance bladder strip contractions to EFS. In presence of 1 and 100 nM of piboserod, the maximal 5-HT-induced potentiations were reduced to 45.0+/-7.9 and 38.7+/-8.7%, respectively. A mean apparent antagonist dissociation constant value (K(B)) of 0.56+/-0.09 nM was determined. These data show the ability of piboserod to antagonize with high potency the enhancing properties of 5-HT on neurally-mediated contractions of isolated human bladder strips. Therefore, the 5-HT(4) receptor might represent an attractive pharmacological target for the treatment of overactive bladder.
Darblade
B
B
Pelvipharm, Domaine CNRS, 1 avenue de la terrasse, Bâtiment 5, 91190 Gif-sur-Yvette, France.
Behr-Roussel
D
D
Gorny
D
D
Lebret
T
T
Benoit
G
G
Hieble
J-P
JP
Brooks
D
D
Alexandre
L
L
Giuliano
F
F
D004558:Electric Stimulation; D006801:Humans; D066298:In Vitro Techniques; D007211:Indoles / Q000494:pharmacology*; D007537:Isometric Contraction / Q000187:drug effects*; D008297:Male; D008875:Middle Aged; D010078:Oxazines / Q000494:pharmacology*; D012701:Serotonin / Q000378:metabolism*; D058832:Serotonin 5-HT4 Receptor Antagonists; D001743:Urinary Bladder / Q000187:drug effects / Q000294:innervation / Q000503:physiopathology*; D014549:Urinary Incontinence / Q000188:drug therapy / Q000378:metabolism / Q000503:physiopathology
D007211:Indoles; D010078:Oxazines; D058832:Serotonin 5-HT4 Receptor Antagonists; D012701:Serotonin; C479132:piboserod