MYOCARDIAL VAGAL-STIMULATION IMPAIRS LOWER ESOPHAGEAL SPHINCTER FUNCTION

Background. Coronary artery disease and gastroesophageal reflux diseas e frequently coexist, but a direct pathophysiologic link has not been established. Methods. This study examines the effect of myocardial vag al receptor stimulation on lower esophageal sphincter (LES) tone in ei ght adult mongrel dogs, each acting as its own control. Pharmacologic stimulation was carried out by the application of 1 cm gauze patches s oaked in nicotine (200 mu g/ml) to the epicardium. Epicardial vagal re ceptors were stimulated mechanically by digital friction. Results. Pha rmacologic stimulation produced a rapid fall in LES tone Srom a mean ( SEM) of 12.6 (1.5) to 8.6 (0.9) sphinctometer units (p = 0.007). Mecha nical stimulation also produced a rapid fall from 12.0 (1.5) sphinctom eter units to 6.8 (0.7) (p = 0.007). Both were associated with a drop in mean arterial blood pressure and heart rate. Sham patches soaked in sterile water produced no effects. Conclusions. These data suggest a direct vagal reflex linking the myocardium and the LES that may explai n the high incidence of gastroesophageal reflux in patients with hear disease.