Effects of caffeine on gastrointestinal myoelectric activity and colonic spike activity in dogs

Background: Caffeine is known to produce various effects on the gastrointes tinal tract. Few studies have, however. investigated the effects of caffein e on gastrointestinal myoelectric activity under physiologic conditions. Th e aims of this study were to investigate the effects of caffeine on colonic motility (spike activity) and gastric and jejunal slow waves in conscious dogs. Methods: The study was performed in eight healthy female hound dogs ( 15-20 kg) in which one pair of electrodes was implanted on the serosa of th e stomach, one pair on the proximal jejunum. and another pair on the ascend ing colon. The protocol consisted of a 60-min recording as base line and a 90-min recording after intravenous injection of saline, a low dose of caffe ine (125 mg), or a high dose of caffeine (250 mg). Results: In the colon th ere was a significant increase in the number of spike bursts per minute aft er the injection of both the low (6.69 +/- 1.27 versus 8.22 +/- 1.31, P < 0 .05) and the high dose (4.38 +/- 1.23 versus 6.92 +/- 0.98. P < 0.05) of ca ffeine. The increase in the total energy of spikes per minute after the inj ection of the high dose of caffeine was significantly higher than that afte r the low dose of caffeine (41.2 +/- 14.6 versus 133.4 +/- 39.2, P < 0.05). The characteristics of the gastric and jejunal slow waves were, however. n ot affected by caffeine. Conclusion: Caffeine increases spike activity in t he colon, and its effect may be dose-dependent. Gastric and jejunal slow wa ves are not affected by caffeine.