Clonidine inhibits gastric motility in the rat.

We have studied the effect of clonidine on gastric motility, by examining the effect on gastric emptying of indigestible solids. In Wistar rats, either clonidine or saline was injected intraperitoneally, and ten steel balls (1.0 mm in diameter) were inserted into the stomach. Gastric emptying was examined at 3 h. Clonidine delayed gastric emptying of steel balls (ED50 = 0.0071 [95% confidence interval: 0.0033-0.013) mg kg-1). Yohimbine, but not naloxone, significantly antagonized the inhibitory effect of clonidine. We conclude that clonidine inhibits gastric motility through the alpha 2 adrenoceptor.