title: Characteristics of P2 (nucleotide) receptors mediating contraction and relaxation of rat aortic strips: possible physiological relevance.
abstract: ATP and ADP relaxed rat aortic strips precontracted with noradrenaline by an endothelium-dependent mechanism. 5'-AMP was much less potent and adenosine was essentially without effect. The metabolically stable analogues alpha,beta-methylene ATP and beta,gamma-methylene ATP further contracted precontracted aorta. Aortic strips, which had not been precontracted with noradrenaline, contracted when exposed to either ATP or alpha,beta-methylene ATP, the latter nucleotide being much more potent than the former. Removal of the endothelium increased the contractions to ATP. ANAPP3 had no effect on the endothelium-dependent relaxations produced by ATP but it antagonized contractions produced by alpha,beta-methylene ATP. These results provide evidence for the possible existence of two subtypes of P2 receptors in rat aorta; a P2 receptor mediating contraction residing on smooth muscle which can be antagonized by ANAPP3 and where alpha,beta-methylene ATP is more potent than ATP, and a P2 receptor mediating relaxation located on the endothelium which cannot be antagonized by ANAPP3 and where ATP is much more potent than alpha,beta-methylene ATP.
mesh_terms: D000244:Adenosine Diphosphate / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D001013:Aorta, Thoracic / Q000187:drug effects; D001158:Arteries / Q000187:drug effects; D004727:Endothelium / Q000187:drug effects; D005260:Female; D066298:In Vitro Techniques; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009126:Muscle Relaxation / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000502:physiology*; D051381:Rats; D011919:Rats, Inbred Strains; D017981:Receptors, Neurotransmitter / Q000502:physiology*; D011983:Receptors, Purinergic
chemical_list: D017981:Receptors, Neurotransmitter; D011983:Receptors, Purinergic; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate