PT - JOURNAL ARTICLE AU - H Moritoki AU - T Kanbe AU - M Maruoka AU - M Ohara AU - Y Ishida TI - Potentiation by dipyridamole of the inhibition of guinea-pig ileum twitch response caused by adenine derivatives. DP - 1978 Feb 01 TA - Journal of Pharmacology and Experimental Therapeutics PG - 343--350 VI - 204 IP - 2 4099 - http://jpet.aspetjournals.org/content/204/2/343.short 4100 - http://jpet.aspetjournals.org/content/204/2/343.full SO - J Pharmacol Exp Ther1978 Feb 01; 204 AB - The inhibition actions of adenosine and adenine nucleotides, such as ATP, AMP and cyclic AMP, on contractions of guinea-pig from ileum induced by transmural stimulation were potentiated by dipyridamole, whereas those of inosine, morphine and tetrodotoxin were not affected. Tritium activity, accumulated during incubation of the ileal segments with [3H]adenosine, was reduced by dipyridamole. The adenosine added was degraded to inosine and then hypoxanthine during incubation, with the ileal segments, thereby restoring the twitch response of the ileal segments. In the presence of dipyridamole, the degradation of adenosine and the recovery of the twitch response was retarded. Thus, dipyridamole may potentiate the inhibitory actions of adenosine and adenine nucleotides on the twitch response of the ileum by inhibiting both the accumulation and the degradation of adenosine.