[Function of the urinary bladder detrusor after injection of botulinic toxin]

The effect of botulinic toxin of type A (BoNT) on urinary bladder (UB) function was studied during operation in situ in healthy rats using the method of infusion cystomanometry after a single injection of the toxin into the UB wall 3 to 30 days after the injection. Contractility of the muscular fragments in vitro was assessed in the isometric regimen in electric stimulation, depolarization of cellular membranes by ion [K+] excess, addition of noradrenalin (10(-5) M). In response to botulinic toxin injection 47-64% rats vs control animals (23%) operated on without toxin had no phasic UB contractions, detrusor pressure (Pdet) after the infusion was higher which indicated retension. In rats with intact UB contractility, contractions were stronger (Pdet 24-34 cm H2O), but rare (3-5/min) vs controls (19 cm H2O, 5/min, respectively). Contractility in vitro in response to electric stimulation regressed by 60-85% after toxin infusion. Contractility in solution [K+] regressed less (by 65, 36, 16% in 3, 10 and 30 days, respectively). No significant changes of noradrenalin-induced reactions were found. The results illustrate possible direct myogenic effect of the toxin on detrusor muscle.