Influence of coronavirus (transmissible gastroenteritis) infection on jejunal myoelectrical activity of the neonatal pig.

Four silver-silver chloride electrodes were surgically implanted at 5-cm intervals on the jejunal serosa of 7 neonatal pigs. Daily recordings, 7 h in duration, were made from each piglet beginning 3 days after surgery. Characteristic migrating motility complexes and short, distinct (2.5-5.0 s), rapidly aboral migrating bursts of intense spike activity ("migrating action potential complexes") were seen in all preinfection recordings. Piglets were inoculated with a 1-ml oral dose of a 0.1% gut suspension from coronavirus (transmissible gastroenteritis) infected pigs. This resulted in inappetence, vomiting, and diarrhea, most marked on the second day postinfection, but which had abated by the third day. When compared to recordings from both fed and fasted noninfected (control) animals, infection significantly altered jejunal myoelectrical activity by (a) shortening the duration of the migrating motility complex on day 1 postinfection and prolonging it on day 2, (b) increasing the number of abnormal activity fronts, and (c) decreasing the number of migrating action potential complexes. Slow wave frequency and the duration of phase 3 of the migrating motility complex were unaffected. When compared to fed control animals, infected piglets also showed a slight shortening of phase 1 of the migrating motility complex on day 1 postinfection and a prolongation on days 2 and 3, as well as a shortening of phase 2 on the second and third days postinfection. Changes in myoelectrical activity were not solely due to decreases in food intake, as abnormalities persisted when food intake returned to normal on postinfection day 3, and disruption of the activity front and migrating motility complex duration were purely transmissible-gastroenteritis-virus-induced phenomena. These findings suggest that infection with transmissible gastroenteritis virus disrupts organized propulsive activity in the jejunum of the neonatal pig.