Piboserod (SB 207266), a selective 5-HT4 receptor antagonist, reduces serotonin potentiation of neurally-mediated contractile responses of human detrusor muscle

• Published in: World journal of urology 2005-07, Vol.23 (2), p.147-151
• Main Authors: DARBLADE, B, BEHR-ROUSSEL, D, GORNY, D, LEBRET, T, BENOIT, G, HIEBLE, J.-P, BROOKS, D, ALEXANDRE, L, GIULIANO, F
• Format: Article
• Language: English
• Subjects: Biological and medical sciences; Electric Stimulation; Humans; In Vitro Techniques; Indoles - pharmacology; Isometric Contraction - drug effects; Male; Medical sciences; Middle Aged; Nephrology. Urinary tract diseases; Oxazines - pharmacology; Serotonin - metabolism; Serotonin 5-HT4 Receptor Antagonists; Urinary Bladder - drug effects; Urinary Bladder - innervation; Urinary Bladder - physiopathology; Urinary Incontinence - drug therapy; Urinary Incontinence - metabolism; Urinary Incontinence - physiopathology; Urinary system involvement in other diseases. Miscellaneous; Urinary tract. Prostate gland
• ISSN: 0724-4983; 1433-8726
• DOI: 10.1007/s00345-005-0499-z

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.