Abstract
It has been generally accepted that adenine nucleotides exhibit a smooth muscle relaxing action and this is caused by adenosine moiety of their molecules (1-4). However, as shown by Stafford (1), Bennet (5) and Deuticke (6), guinea-pig uterus contracts in response to adenine nucleotides as well as to adenosine. Furthermore, several workers (7-11) observed on rat uterus or goldfish intestine that ADP and ATP exhibited a contraction but 5'-AMP or adenosine did not.
On the other hand, it has been reported that the pretreatment of ATP or cyclic 3', 5'-AMP modified the contractile responses of adenine or uridine nucleotides, though the influences varied in each cases (3, 10, 11). Although these sensitization mechanisms are not still clarified, these studies will give a clue to the elucidation of the contractile mechanism of ATP.
In order to know the mechanism of smooth muscle contraction induced by adenine nucleotides or adenosine, present study was performed on the effects of 5'-AMP and its related compounds on the ATP-induced contraction of isolated guinea-pig ileum.
