Enteric nerve stimulation evokes a premature colonic migrating motor complex in mouse

Abstract

The effects of enteric nerve stimuli were investigated on spontaneously occurring colonic migrating motor complexes (CMMCs) in isolated mouse colon. Changes in circular smooth muscle tension were recorded simultaneously from the proximal, mid and distal regions of an in vitro preparation of whole mouse colon at 36 ± 1°C. The CMMCs were recorded from all preparations with a mean interval between contractions ranging from 135.2 ± 9.3 to 163.3 ± 22.4 s. The CMMCs migrated spontaneously from the proximal to distal colon and were abolished by tetrodotoxin (1 μmol L-1). In approximately half of all trials (57 of 103, n = 31), trains of stimuli (20 Hz, 2-5 s, 1 ms, 40-70 V) delivered to the mid or distal regions of colon, during the intervals between CMMCs, elicited a premature CMMC. However, similar trains of stimuli delivered to the proximal colon were without similar effects (33 trials, n = 13). It is suggested that in isolated whole mouse colon, CMMCs can be evoked prematurely by trains of electrical stimuli applied to the enteric nerves. The observation that nerve stimuli failed to evoke a premature CMMC from the proximal colon suggests that selective activation of functional ascending pathways may be required to initiate a premature CMMC.