Abstract
Pharmacological analysis was made on the relaxant effect of ATP and its related nucleotides to guinea-pig taenia coli . ATP and ADP were equally the most potent among the compounds tested in causing relaxation of the taenia . The relaxant responses to these compounds had rapid onsets as that to electrical stimulation of the intrinsic non-adrenergic inhibitory nerves . The relaxant effect of ATP (10-6-10-5g/ml) was completely prevented by either imidazole (3.5×times;10-3g/ml) or phentolamine (5×times;10-6g/ml), though the relaxation due to stimulation of the intrinsic inhibitory nerves was not influenced by these blocking agents. These results are rather against the concept that ATP or its related nucleotide is the transmitter substance of the intrinsic non-adrenergic inhibitory nerves.
