EFFECT OF NITROBLUE TETRAZOLIUM ON NO SYNTHASE AND MOTOR FUNCTION OF OPOSSUM ESOPHAGUS

Nitric oxide mediates neuromuscular events in the opossum esophagus. T he NADPH diaphorase stain is used to localize nitric oxide synthase-co ntaining enteric neurons. Cells stain by the NADPH diaphorase techniqu e because they reduce nitroblue tetrazolium to the visible formazan, T he effects of nitroblue tetrazolium on neuromuscular function and nitr ic oxide synthase of esophageal muscle were studied. The NADPH diaphor ase stain was performed. Nitroblue tetrazolium inhibited lower esophag eal sphincter relaxation, abolished the latency gradient of the off re sponse, and inhibited nitric oxide synthase. The NADPH diaphorase tech nique stained myenteric plexus nerve cell bodies and nerve processes. Nitroblue tetrazolium is not a nonspecific muscle or nerve toxin, as n erve-mediated cholinergic responses, responses to exogenous nitric oxi de, and responses to myogenic stimulation were maintained after nitrob lue tetrazolium abolished the off response and lower esophageal sphinc ter relaxation. Nitroblue tetrazolium inhibits nitric oxide-mediated e vents and nitric oxide synthase. It stains neurons in the esophageal m yenteric plexus.