Effects of esophageal capsaicin instillation on acid induced excitation of secondary peristalsis in humans

Abstract

Background/Aim: Esophageal instillation of capsaicin or hydrochloric acid enhances secondary peristalsis. Our aim was to investigate whether intra-esophageal capsaicin infusion can influence symptom perception and physiological alteration of secondary peristalsis subsequent to acid infusion. Methods: Secondary peristalsis was induced by mid-esophagus injections of air in 18 healthy subjects. Two different sessions including esophageal infusion of hydrochloric acid (0.1N) following pretreatment with saline or capsaicin-containing red pepper sauce were randomly performed at least one week apart. Symptoms of heartburn and secondary peristalsis were determined and compared between each study session. Results: The intensity of heartburn symptom subsequent to acid infusion was significantly reduced after capsaicin infusion as compared with saline infusion (54±3 vs 61±3; P=0.03). Capsaicin infusion significantly increased the threshold volume of secondary peristalsis to rapid air injections subsequent to esophageal acid infusion (8.0±0.5mL vs 4.4±0.3mL; P<0.0001). The frequency of secondary peristalsis subsequent to acid infusion was significantly decreased after capsaicin infusion as compared to saline infusion (70% [60-82.5%] vs 80% [70-90%]; P=0.03). Capsaicin infusion significantly decreased the pressure wave amplitude of secondary peristalsis subsequent to acid infusion during rapid air injections (90.6±8.7 mmHg vs 111.1±11.1 mmHg; P=0.03). Conclusions: Capsaicin appears to desensitize the esophagus to acid induced excitation of secondary peristalsis in humans, which is probably mediated by rapidly adapting mucosal mechanoreceptors. High capsaicin-containing diet might attenuate normal physiological response to abrupt acid reflux by inhibiting secondary peristalsis.