Comparison of the actions of ATP and UTP and P(2X1) receptors in smooth muscle of the rat tail artery.
The actions of ATP and uridine 5'-triphosphate (UTP) were compared at P2X1 receptors in acutely dissociated smooth muscles cells of the rat tail artery. ATP (30 nM-100 microM) and UTP (1 microM-1 mM) elicited concentration-dependent inward currents. ATP was approximately 100-fold more 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 concentration-dependent and in most cells could be fitted by two exponentials. The P2X receptor antagonists suramin (100 microM) and pyridoxalphosphate-6-azophenyl-2',4'-disulphonic acid (PPADS, 5 microM) inhibited responses to both ATP and UTP. An action of UTP at P2X1 receptors has not previously 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 these cells, the P2X1 receptor.
McLaren
G J
GJ
Department of Physiology and Pharmacology, University of Strathclyde, Glasgow, UK. gerald.mclaren@strath.ac.uk
Sneddon
P
P
Kennedy
C
C
D000255:Adenosine Triphosphate / Q000494:pharmacology*; D000818:Animals; D004305:Dose-Response Relationship, Drug; D007700:Kinetics; D008297:Male; D009131:Muscle, Smooth, Vascular / Q000187:drug effects* / Q000378:metabolism; D018408:Patch-Clamp Techniques; D010975:Platelet Aggregation Inhibitors / Q000494:pharmacology; D058910:Purinergic P2 Receptor Agonists; D058919:Purinergic P2 Receptor Antagonists; D011732:Pyridoxal Phosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D058469:Receptors, Purinergic P2X; D013498:Suramin / Q000494:pharmacology; D013623:Tail / Q000098:blood supply; D014544:Uridine Triphosphate / Q000494:pharmacology*
D010975:Platelet Aggregation Inhibitors; D058910:Purinergic P2 Receptor Agonists; D058919:Purinergic P2 Receptor Antagonists; D058469:Receptors, Purinergic P2X; C077792:pyridoxal phosphate-6-azophenyl-2',4'-disulfonic acid; D011732:Pyridoxal Phosphate; D013498:Suramin; D000255:Adenosine Triphosphate; D014544:Uridine Triphosphate