Effects of inhibitors of prostaglandin synthesis on rebound excitation of guinea-pig small bowel.

The prostaglandin synthetase inhibitors indomethacin and acetyl salicylic acid did not affect the post-stimulus rebound excitation of guinea-pig duodenal and jejunal circular muscle with transmural electrical stimulation at 1 min intervals. In the absence of any drug, sequential time-dependent changes in amplitude of the rebound contractions were: (1) progressive increase during first 10 min, (2) a plateau at 30 min, (3) progressive decline to almost no response over 3 h. The results indicate that, in the circular muscle layer, prostaglandin synthesis is not required for production of the rebound response following electrical stimulation of inhibitory neurons.