Gj. Mclaren et al., COMPARISON OF THE ACTIONS OF ATP AND UTP AT P-2X1 RECEPTORS IN SMOOTH-MUSCLE OF THE RAT TAIL ARTERY, European journal of pharmacology, 351(1), 1998, pp. 139-144
The actions of ATP and uridine 5'-triphosphate (UTP) were compared at
P-2X1 receptors in acutely dissociated smooth muscles cells of the rat
tail artery. ATP (30 nM-100 mu M) and UTP (1 mu M-1 mM) elicited conc
entration-dependent inward currents. ATP was approximately 100-fold mo
re potent than UTP. In both cases, currents were activated within 3 ms
of agonist application and had similar time-courses of activation and
inactivation. The decay of responses for both agonists was concentrat
ion-dependent and in most cells could be fitted by two exponentials. T
he P-2X receptor antagonists suramin (100 mu M) and pyridoxalphosphate
-6-azophenyl-2',4'-disulphonic acid (PPADS, 5 mu M) inhibited response
s to both ATP and UTP. An action of UTP at P-2X1 receptors has not pre
viously been reported. However, since the responses to ATP and UTP had
similar time-courses and as PPADS and suramin inhibited both agonists
, it is concluded that ATP and UTP are acting at the same site in thes
e cells, the P-2X1 receptor. (C) 1998 Elsevier Science B.V. All rights
reserved.