Modification of small bowel mechanosensitivity by intestinal fat.

Abstract

Lipids may exacerbate symptoms induced by gut stimuli. To determine the mechanism whereby fat exerts this effect. Twenty four healthy subjects were studied during fasting. We measured perception (0-6 scale) in response to jejunal balloon distension and transmucosal electrical nerve stimulation; phasic stimuli (one minute) were randomly applied at five minute intervals during intestinal infusion (2 ml/min) of saline and then Intralipid 2 kcal/min (high fat; n=8 subjects), Intralipid 0.5 kcal/min (low fat; n=8), or saline (n=8). Intestinal lipids increased the perception of jejunal distension regardless of concentration (by 53% with high fat, 49% with low fat, and 17% with saline; p<0.05 for both fat loads). This effect could not be attributed to changes in intestinal compliance as intraballoon pressures remained unchanged during lipid infusion (2% change; NS). Sensitisation induced by lipids seemed to be specifically related to intestinal mechanoreceptors because electrical stimulation, which non-specifically activates gut afferents, was perceived equally during saline and lipid administration (10%, 11%, and 15% change during high fat, low fat, and saline, respectively; NS). Physiological amounts of lipids heighten intestinal sensitivity by modulating intestinal mechanoreceptor response.