Inhibitory effect of nicorandil on the contraction of isolated human urinary bladder detrusor muscle.

This study was performed to determine whether the antianginal drug nicorandil relaxes isolated human detrusor muscle. Ten strips of detrusor muscle obtained from 10 pediatric patients who underwent surgery on the urinary bladder were contracted with 80 mM potassium chloride (KCl) before and after incubation with four concentrations of nicorandil (100, 200, 400 and 800 microM). The percent inhibition by nicorandil of the height and area under the curve (AUC) of KCl-induced contractions of the detrusor strips was calculated. The effect of glibenclamide (10 microM) on nicorandil (800 microM)-induced inhibition of KCl-induced detrusor contractions was also studied. Nicorandil caused a concentration-dependent inhibition of KCl-induced contractions of the detrusor strips. The percent inhibition of the height of KCl-induced contractions of the detrusor by nicorandil was significant at concentrations of 200, 400 and 800 microM. The percent inhibition of the AUC for KCl-induced detrusor contractions was significant at all four concentrations of nicorandil used. Glibenclamide reversed the inhibitory effect of 800 microM nicorandil on KCl-induced detrusor contractions. These results suggest that nicorandil inhibits KCl-induced contractions of isolated human detrusor muscle and may therefore be useful in clinical conditions requiring detrusor muscle relaxation.