TY - JOUR T1 - Potentiation by dipyridamole of the inhibition of guinea-pig ileum twitch response caused by adenine derivatives. JF - Journal of Pharmacology and Experimental Therapeutics JO - J Pharmacol Exp Ther SP - 343 LP - 350 VL - 204 IS - 2 AU - H Moritoki AU - T Kanbe AU - M Maruoka AU - M Ohara AU - Y Ishida Y1 - 1978/02/01 UR - http://jpet.aspetjournals.org/content/204/2/343.abstract N2 - 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. ER -