Myoelectric activity of the small intestine in enterotoxin-induced diarrhea of calves.

Electrodes were surgically implanted at 15-cm intervals in the jejunum and ileum of 4 healthy neonatal calves so that myoelectric activity could be recorded on 2 consecutive days. On the first day, each calf received a control treatment, and myoelectric activity was recorded for 340 minutes. Phase I was recorded for a mean of 175.8 +/- 22.8 minutes (51.5%), phase II for 124 +/- 27.4 minutes (36.5%), and phase III for 40.3 +/- 6 minutes (11.9%). On the second day, each calf was treated with approximately 200 micrograms of heat-stable enterotoxin (STa) of Escherichia coli orally. All calves developed diarrhea after the administration of STa. Phase I was recorded for a mean of 92.5 +/- 42.3 minutes (27.2%), phase II for 227.3 +/- 52.5 minutes (66.9%), and phase III for 20.3 +/- 11.4 minutes (6.0%). Increase in phase II and decrease in phases I and III after STa administration were significant (P less than 0.05). Duration of the migrating myoelectric complex was longer after STa administration (median, 64 minutes), compared with the control treatment (median, 54 minutes). Minute rhythms, recorded on the day of toxin administration, ranged from 49 to 153 minutes. There was no difference between the number of migrating action potential complexes on the control days (range, 1 to 10), compared with those on treatment days (range, 1 to 14). These findings are suggestive that enterotoxin-induced diarrhea of calves is accompanied by increased total spiking activity and minute rhythms in the distal portion of the jejunum and ileum.