IN-VIVO AND IN-VITRO INFLUENCE OF HUMAN RECOMBINANT HEMOGLOBIN ON ESOPHAGEAL FUNCTION

The purpose of the present investigation was to examine the influence of a nitric oxide scavenger, hemoglobin (Hb), on esophageal function. Intraluminal pressures of anesthetized opossums were recorded from low er esophageal sphincter (LES) and 1, 5, and 9 cm above the LES. The in fluence of a representative Kb-based oxygen carrier was examined on sw allowing-induced esophageal peristalsis and LES relaxation. In in vitr o studies, LES relaxation and esophageal peristaltic contractions were induced by the activation of nonadrenergic noncholinergic (NANC) neur ons by electrical field stimulation (EFS). Hb caused significant impai rment in swallowing- and EFS-induced LES relaxation and a significant increase in the speed of esophageal peristalsis. In some experiments, swallowing caused simultaneous contractions in the esophagus following Hb administration. Although Hb completely blocked LES relaxation by N O and significantly attenuated that by NANC nerve stimulation, it had no significant effect on isoproterenol-induced LES relaxations. The da ta support the role of NO in LES relaxation and esophageal peristalsis . This esophageal model may be important in understanding the influenc e of NO inhibitors and scavengers in gastrointestinal motility.