Stimulation of esophageal mechanoreceptors is dependent on rate and duration of distension.

We randomly compared rapid (170 ml/s) and slow (0.7 ml/s) rates of balloon distension in 19 volunteers (9 male, 10 female) using a latex balloon (length 3 cm) positioned 5 cm proximal to the lower esophageal sphincter. The balloon was inflated/deflated (1-s dwell; 5- to 10-s interval) with increasing 2-ml volumes during rapid inflation studies and progressively distended during slow inflation studies while subjects blindly indicated feeling, rated as follows: 0 (no sensation); 1 (aware of balloon, but no discomfort); 2 (pain or discomfort). In a second set of studies, the balloon was left inflated for 60 s at a volume 2 ml below that producing sensation 1, and time until a change in sensation was recorded. This was repeated at a volume 2 ml below that producing sensation 2. Mean volume to sensation 1 with slow inflation was 14.6 +/- 1.2 ml (SE) and with rapid inflation was 8.5 +/- 0.8 ml (P < 0.001). Mean volume to sensation 2 with slow inflation was 23.7 +/- 1.0 ml and with rapid inflation was 17.4 +/- 1.0 ml (P < 0.001). With sustained (60 s) inflation, most subjects noted increasing sensation, independent of initial inflation rate. We conclude that distal esophageal sensory perception (both awareness and discomfort) is dependent on rate of stimulation of mechanoreceptors. A sustained distension stimulus appears to recruit additional receptors and increase the level of sensory awareness.