Effect of xylazine, cisapride, and naloxone on myoelectric activity of the ileocecocolic area in cows.

The effect of xylazine, cisapride, and naloxone on myoelectric activity of the ileum, cecum, and proximal loop of the ascending colon (PLAC) was determined in 4 healthy Jersey cows implanted with 8 pairs of bipolar electrodes. A 4 x 4 Latin square design was used. The treatments included xylazine (0.04 mg/kg of body weight), cisapride (0.08 mg/kg), naloxone (0.05 mg/kg), and 0.9% sodium chloride solution (20 ml). All treatments were administered i.v. during early phase I of the migrating myoelectric complex in the ileum. Myoelectric activity was recorded for 4 hours after treatment, and data were analyzed for each hour separately. Xylazine significantly (P < 0.05) increased the duration of phase I of the first migrating myoelectric complex in the ileum to 220.72 +/- 26.89 minutes, compared with 30.91 +/- 10.11 minutes after administration of 0.9% sodium chloride solution. The number of cecocolic spikes per minute per electrode and the duration of cecocolic spike activity (percentage of recording time) were significantly (P < 0.05) decreased for the first 3 hours, and the number of propagated spike sequences in the cecum and PLAC was significantly (P < 0.05) decreased for the first 2 hours after administration of xylazine. Significant difference was not found between control and either cisapride or naloxone treatment of healthy cows. However, during hour 1 after treatment with cisapride, number of spikes per minute, duration of spike activity, and number of propagated spike sequences were highest, compared with the other treatments.(ABSTRACT TRUNCATED AT 250 WORDS)