An in vitro study on human ureteric smooth muscle with the alpha1-adrenoceptor subtype blocker, tamsulosin.
OBJECTIVE
To study the effects of tamsulosin on ureteric contractions and its effects on the basal tone of human ureteric specimens, as clinical trials with tamsulosin have shown promising results in the spontaneous expulsion of lower ureteric calculus, but the mechanism of action of tamsulosin in the expulsion of ureteric calculus has not been elucidated in in-vitro studies on human ureters.


METHODS
Human mid-ureteric specimens were obtained from live kidney donors. The specimen was transported in Krebs' solution and the isometric contraction of human ureteric smooth muscle was recorded in the presence of tamsulosin. Ureteric rings from 19 kidney donors were studied.


RESULTS
At 100 microm tamsulosin the frequency of ureteric contraction was blocked completely, or the contraction frequency was reduced in 89% of specimens. There was no change in the frequency or in the amplitude of contraction in the remaining specimens. The basal tone of the ureter was reduced in 16% of the specimens.


CONCLUSIONS
Our results suggest that peristaltic activity in human ureteric smooth muscle is inhibited by tamsulosin. The effect of tamsulosin on basal tone is marginal.
Rajpathy
John
J
British Oxygen Company Limited, Chennai, India.
Aswathaman
Karthikeyan
K
Sinha
Maneesh
M
Subramani
Sathya
S
Gopalakrishnan
Ganesh
G
Kekre
Nitin S
NS
D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009119:Muscle Contraction / Q000187:drug effects*; D009130:Muscle, Smooth / Q000187:drug effects* / Q000502:physiology; D013449:Sulfonamides / Q000494:pharmacology*; D000077409:Tamsulosin; D014513:Ureter / Q000187:drug effects*
D000317:Adrenergic alpha-Antagonists; D013449:Sulfonamides; D000077409:Tamsulosin