Acute effects of serotonin on rat bladder contractility.
BACKGROUND
The purpose of this study is to investigate in vitro the effects of serotonin on the rat detrusor. In particular, it examines which drugs inhibit the serotonin-induced detrusor contractions.


METHODS
Isometric tension changes of isolated rat bladder muscle strips were recorded in an organ bath using a force transducer. Acute effects of serotonin (0.0001-0.01 mM) on resting tension were assessed. Electrical field stimulation (EFS); bethanechol (0.0001-0.01 mM); ATP (1-3 mM)- or KCl (63.5-254 mM)-induced contractions using an application in an organ bath were compared with serotonin-induced contractions. In order to examine the action mechanism of serotonin-induced stimulation, EFS-, bethanechol-, ATP- or KCl-induced contraction on serotonin treatment (0.001 mM) was assessed and serotonin (0.001-0.1 mM) was cumulatively added to the organ bath following preincubation with propranolol, ketanserin, tropisetron, propiverine, sodium nitroprusside or doxazosin.


RESULTS
The serotonin-induced response has two phases: an initial transient contraction and a prolonged tonic phase. Serotonin produced a reversible and dose-dependent contraction of the detrusor strips. Responses to bethanechol significantly increased with a concentration of 0.001 mM serotonin (p < 0.05). There was no effect on the responses to ATP, KCl, or EFS on 0.001 mM serotonin. The 5-HT(2) receptor is mainly responsible for serotonin-induced contractions of the detrusor (p < 0.05), while the 5-HT(1) receptor is partially responsible. Doxazosin and propiverine each significantly suppressed the response to serotonin, while sodium nitroprusside and tropisetron each had no effect (p < 0.05).


CONCLUSIONS
Because the 5-HT(2) antagonist blocked the effect of serotonin-induced bladder contractions and the stimulation of the adrenoreceptors, the 5-HT(2) antagonist seems to improve lower urinary tract symptoms.
Kim
Hyung Jee
HJ
Department of Urology, Dankook University College of Medicine, Cheonan, Chungnam, Korea. shimwon2@anseo.dankook.ac.kr
Lee
Gilho
G
Kim
Dong Hee
DH
Lee
Suk Jae
SJ
Yoon
Duck Ki
DK
Cho
Jae Heung
JH
D000818:Animals; D018723:Bethanechol / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004558:Electric Stimulation; D008297:Male; D023421:Models, Animal; D009119:Muscle Contraction / Q000187:drug effects* / Q000502:physiology; D009130:Muscle, Smooth / Q000187:drug effects / Q000502:physiology; D011336:Probability; D051381:Rats; D017207:Rats, Sprague-Dawley; D012016:Reference Values; D012680:Sensitivity and Specificity; D012701:Serotonin / Q000494:pharmacology*; D001743:Urinary Bladder / Q000187:drug effects*
D018723:Bethanechol; D012701:Serotonin