The Effect of Caffeine, Theophylline and Adenosine on the Colonic Transit Time of Guinea Pigs

Moon, Jong Tae; Choi, Eun Ju; Kim, Yung Gyun; Kim, Hee Sun; Park, Hyo Jin

Abstract

BACKGROUND/AIMS: Caffeine and theophylline are adenosine receptor antagonists and they are also non-specific phosphodiesterase inhibitors. We aimed to estimate the effects of caffeine and theophylline on the colonic activity of guinea pigs, and we investigated whether caffeine or theophylline has an offsetting effect on adenosine.
METHODS
The colon (approximately 10 cm from the guinea pig's anus) was extracted; both ends of it were connected to a chamber that contained K-H solution. Artificial feces was inserted into the oral side of the lumen, and it was moved toward the anal side. We observed a total length of 8 cm of the colon and recorded the time taken for the artificial feces to move each 2 cm.
RESULTS
Caffeine decelerated the transit with a dose dependant pattern, but theophylline had no significant effect on the transit time. Adenosine significantly increased the colonic transit time at only high concentrations. When caffeine (10(-6) M) was administered with adenosine (10(-3) M), the colonic transit time was significantly delayed compared with administering caffeine alone. When caffeine was administered with adenosine, the colonic transit time was significantly shortened compared with administering adenosine alone at 10(-3) M, and this didn' change after theophylline was added.
CONCLUSIONS
Caffeine or adenosine inhibits colonic transit, but theophylline does not affect colonic motility. Caffeine offsets the inhibitory effect of adenosine. Caffeine probably delays colonic transit as an intrinsic PDE inhibitor.