Mechanisms of meconium passage: cholinergic stimulation of electromechanical coordination in the fetal colon

OBJECTIVE: Fetal gastrointestinal function develops in utero, with evidence of enhanced motility near-term. Although colonic passage of meconium in utero may be associated with fetal maturation or stress, little is known of the mechanisms potentiating motility. We assessed the effect of bethanechol, a cholinergic prokinetic agent, on colonic muscle muscular contractile and electromyogram (EMG) activity in the near-term ovine fetus. METHODS: Near-term (130 days, n = 8) singleton ovine fetuses were chronically prepared with vascular catheters and three sets of miniature strain gauges and bipolar EMGs on the serosal surface of the transverse colon, left colic flexure, and distal colon. Following a 60-minute control period, fetuses received intravenous bethanechol (60 microg/kg, Low-Beth; 120 microg/kg, High-Beth) at 60 and 180 minutes. Colonic activity was recorded digitally and analyzed for short-duration (2