Figure 13 - Lower esophageal sphincter (LES) relaxation is lost in neuronal nitric oxide synthase (nNOS)-deficient mice.

Note that in wild-type mice pharyngeal stimulation was normal; saline causes LES relaxation. However, in nNOS-deficient animals, LES relaxation is abolished, suggesting that nNOS is the enzymatic source of nitric oxide, which is responsible for swallow evoked LES relaxation.