Fig. 5. Effects of increasing concentrations of SOD (A ) and 100 U/ml catalase (B ) on 10−5m midazolam-induced inhibition of 30 mm KCl-induced relaxation in the presence of atropine and guanethidine (nonadrenergic noncholinergic [NANC] relaxation) of strips from the lower esophageal sphincter. Pretreatment with SOD (100, 200, and 400 U/ml) or catalase did not reverse the midazolam-induced inhibition of the NANC relaxation. Each bar represents the mean from tissues from two animals (A, B ); vertical lines show SD. N indicates the number of strips. *P < 0.05, significantly different from the value in the absence of midazolam.