Figure 8 - a: Effect of nitro-L-arginine methyl ester (L-NAME) on LES relaxation in the opossum in vivo.

Control esophageal manometry illustrates an esophageal body peristaltic contraction and LES relaxation in two separate recording channels. Following the intravenous administration of L-NAME, a selective inhibitor of nitric oxide synthase, the latency prior to the esophageal contraction is shortened, basal LES pressure increased and LES relaxation is abolished. L-arginine, an antagonist of L-NAME, reverses the effects of L-NAME. (Source: Yamato et al.³² with permission from Elsevier.) b: Effect of L-NAME on esophageal peristalsis in the opossum in vivo. Control esophageal manometry (A) demonstrates an esophageal body peristaltic sequence with increasing latency period before each contraction that characterizes peristalsis. In the second sequence (B), the animal has been pretreated with L-NAME, a selective inhibitor of nitric oxide synthase, resulting in a loss of the latency gradient and hence simultaneous esophageal body contractions. Finally in the third panel (C), the animal was pretreated with both L-NAME and atropine (Atr), an antimuscarinic agent, resulting in simultaneous and low-amplitude esophageal contractions.