Effects of capsaicin on esophageal peristalsis in humans using high resolution manometry

Background: Capsaicin-containing red pepper sauce suspension augments esophageal contraction amplitude on conventional manometry. This study used high-resolution manometry (HRM) to investigate if capsaicin infusion modulates segmental esophageal smooth muscle peristalsis in healthy adults. Methods: Sixteen healthy volunteers (mean age 37 years, 14 male) underwent HRM for the evaluation of primary peristalsis and secondary peristalsis using slow and rapid air distensions. Both primary and secondary peristalsis were assessed following infusions of capsaicin-containing red pepper sauce and saline. Key Results: Capsaicin infusion significantly increased heartburn symptoms compared to saline infusion (p < 0.001), and significantly decreased threshold volumes of secondary peristalsis during rapid air distensions (p = 0.02). The frequency of secondary peristalsis during rapid air distensions was significantly increased by capsaicin infusion (p = 0.03). Neither capsaicin infusion (p = 0.06) nor saline infusion (p = 0.27) altered threshold volume during slow air distensions. Capsaicin infusion significantly increased distal contractile integral (DCI) of primary peristalsis (p = 0.04), particularly in the proximal smooth muscle segment (p = 0.048). It enhanced secondary peristalsis during rapid air distensions (p = 0.003) but not during slow air distension (p = 0.23). Saline infusion significantly increased DCI of secondary peristalsis during rapid air distension (p = 0.01). Conclusions and Inferences: Augmentation of distension-induced secondary peristalsis can be modulated by activation of capsaicin-sensitive afferents similar to mechanosensitive afferents. Capsaicin-induced augmentation of primary peristalsis isolates to the cholinergic-mediated proximal smooth muscle segment, which warrants study in ineffective esophageal motility to determine therapeutic potential.