2-fluoro-adp and 8-phenyltheophylline

The pharmacological effects of ATP and of an adenine nucleotide analogue, adenosine 5'-(2-fluorodiphosphate) (ADP-beta-F) on various guinea-pig isolated smooth muscle preparations were investigated. ATP relaxed the taenia coli and the aorta, and contracted the urinary bladder and vas deferens. ADP-beta-F mimicked the effects of ATP on the taenia coli and aorta, but did not contract the bladder or vas deferens. The lack of potency of ADP-beta-F on the bladder was not due to its rapid degradation by ectonucleotidases, as it was degraded more slowly than ATP by both the bladder and the taenia coli. These results are consistent with the suggestion that the P2-purinoceptors mediating contraction of smooth muscle (P2X) are different from those mediating inhibitory effects (P2Y), and suggest that ADP-beta-F is a specific agonist at the P2Y-purinoceptor.

Topics: Adenosine Diphosphate; Adenosine Triphosphate; Animals; Aorta, Thoracic; Colon; Guinea Pigs; In Vitro Techniques; Male; Muscle Relaxation; Muscle, Smooth; Muscle, Smooth, Vascular; Receptors, Purinergic; Theophylline; Vas Deferens