Depressant action of oxybutynin on the contractility of intestinal and urinary tract smooth muscle.
Experiments were carried out in-vitro using segments of guinea-pig ileum, taenia caeci, ureter and detrusor. In the ileum, oxybutynin (30, 100 nM) competitively antagonized acetylcholine-induced contractions but did not alter those induced by histamine. Higher concentrations of oxybutynin (up to 10 microM) induced a non-competitive depression of responses to both agonists and caused a parallel shift to the right of the Ca2+-induced contractions in taenia caeci strips bathed in a Ca2+-free, high-K+ medium. In the ureter, oxybutynin (1-10 microM) impaired rhythmic muscular contractions in normal medium and after CaCl2 addition in Ca2+-free medium. Similarly to verapamil (10, 30 microM), oxybutynin (10, 30 microM) depressed both the cholinergic and non-adrenergic, non-cholinergic components of the electrically-induced contractions of detrusor strips. It is concluded that oxybutynin has anticholinergic properties and, at higher concentrations, exerts a direct spasmolytic activity possibly mediated by blockade of the transmembrane Ca2+ fluxes responsible for smooth muscle contraction.
D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D002122:Calcium Chloride / Q000494:pharmacology; D003864:Depression, Chemical; D004305:Dose-Response Relationship, Drug; D004558:Electric Stimulation; D005260:Female; D006168:Guinea Pigs; D006632:Histamine / Q000494:pharmacology; D066298:In Vitro Techniques; D007422:Intestines / Q000187:drug effects / Q000502:physiology; D008297:Male; D008333:Mandelic Acids / Q000494:pharmacology*; D009119:Muscle Contraction / Q000187:drug effects*; D009130:Muscle, Smooth / Q000187:drug effects*; D010276:Parasympatholytics / Q000494:pharmacology*; D014513:Ureter / Q000187:drug effects / Q000502:physiology; D001743:Urinary Bladder / Q000187:drug effects / Q000502:physiology; D014700:Verapamil / Q000494:pharmacology
D008333:Mandelic Acids; D010276:Parasympatholytics; D006632:Histamine; D014700:Verapamil; C005419:oxybutynin; D002122:Calcium Chloride; D000109:Acetylcholine