title: Effects of disopyramide on detrusor muscle contraction: in vitro experiment and report of 3 cases with disopyramide-induced urinary retention.
abstract: Three cases of disopyramide-induced urinary retention were reported and effects of disopyramide on agonist-induced contraction of detrusor muscle were studied in vitro. Muscle strips were obtained from rabbit bladder body and changes in isometric contraction of the strips were monitored. Acetylcholine, prostaglandin F2-alpha, potassium chloride, barium chloride, adenosine triphosphate and Ca2+ were used as agonists for detrusor muscle contraction. Disopyramide relaxed the contraction elicited by acetylcholine in normal Krebs solution, but exhibited no relaxing effect on contractions induced by prostaglandin F2-alpha, potassium chloride, barium chloride and adenosine triphosphate. In Ca2+-free Krebs solution, basal tension of the strips declined and spontaneous contractile activity was eliminated. Replenishment of 3 mM Ca2+ induced a slow contraction and redevelopment of spontaneous contraction of the strips. Pretreatment of the strips with disopyramide had no inhibitory effect on the Ca2+-induced contraction or on the spontaneous contractile activity in Ca2+-free solution. In normal Krebs solution, acetylcholine (10(-9)-10(-2)M) caused dose-dependent contractions of the detrusor muscle strips. Pretreatment of the strips with disopyramide (10(-5)-10(-3)M) dose-dependently inhibited the acetylcholine-induced contraction in a competitive way. The inhibitory effect of disopyramide on acetylcholine-induced contraction was less potent than that of atropine. We conclude that disopyramide may inhibit detrusor contractile activity mostly by its anticholinergic effect, resulting clinically in micturition disturbance.
mesh_terms: D000109:Acetylcholine / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000494:pharmacology; D000368:Aged; D000369:Aged, 80 and over; D000818:Animals; D001464:Barium / Q000494:pharmacology; D017609:Barium Compounds; D002712:Chlorides; D015237:Dinoprost; D004206:Disopyramide / Q000009:adverse effects*; D005260:Female; D006801:Humans; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects*; D011189:Potassium Chloride / Q000494:pharmacology; D011460:Prostaglandins F / Q000494:pharmacology; D011817:Rabbits; D014525:Urethral Stricture / Q000139:chemically induced*
chemical_list: D017609:Barium Compounds; D002712:Chlorides; D011460:Prostaglandins F; C024986:barium chloride; D001464:Barium; D011189:Potassium Chloride; D000255:Adenosine Triphosphate; D015237:Dinoprost; D004206:Disopyramide; D000109:Acetylcholine