title: Antagonism of P2Y1-induced vasorelaxation by acyl CoA: a critical role for palmitate and 3'-phosphate.
abstract: OBJECTIVE
  Acyl derivatives of CoA have been shown to act as antagonists at human platelet and recombinant P2Y1 receptors, but little is known about their effects in the cardiovascular system. This study evaluated the effect of these endogenous nucleotide derivatives at P2Y1 receptors natively expressed in rat and porcine blood vessels.
  
  
  METHODS
  Isometric tension recordings were used to evaluate the effects of CoA, acetyl CoA, palmitoyl CoA (PaCoA) and 3'-dephospho-palmitoyl-CoA on concentration relaxation-response curves to ADP and uridine triphosphate (UTP). A FlexStation monitored ADP- and UTP-evoked calcium responses in HEK293 cells.
  
  
  RESULTS
  Acetyl CoA and PaCoA, but not CoA, inhibited endothelium-dependent relaxations to ADP with apparent selectivity for P2Y1 receptors (over P2Y(2/4) receptors) in rat thoracic aorta; PaCoA was more potent than acetyl CoA (331-fold vs. fivefold shift of ADP response curve evoked by 10 μM PaCoA and acetyl CoA, respectively); the apparent pA2 value for PaCoA was 6.44. 3'-dephospho-palmitoyl-CoA (10 μM) was significantly less potent than PaCoA (20-fold shift). In porcine mesenteric arteries, PaCoA and the P2Y1 receptor antagonist MRS2500 blocked ADP-mediated endothelium-dependent relaxations; in contrast, they were ineffective against ADP-mediated endothelium-independent relaxation in porcine coronary arteries (which does not involve P2Y1 receptors). Calcium responses evoked by ADP activation of endogenous P2Y1 receptors in HEK293 cells were inhibited in the presence of PaCoA, which failed to alter responses to UTP (acting at endogenous P2Y(2/4) receptors).
  
  
  CONCLUSIONS
  Acyl derivatives of CoA can act as endogenous selective antagonists of P2Y1 receptors in blood vessels, and this inhibitory effect critically depends on the palmitate and 3'-ribose phosphate substituents on CoA.
authors.affiliation: Cardiovascular Research Group and Lipid Signalling, School of Biomedical Sciences, University of Nottingham, Nottingham, UK.
authors.forename: E
authors.initials: E
authors.lastname: Alefishat
authors.forename: S P H
authors.initials: SP
authors.lastname: Alexander
authors.forename: V
authors.initials: V
authors.lastname: Ralevic
mesh_terms: D000105:Acetyl Coenzyme A / Q000494:pharmacology; D000214:Acyl Coenzyme A / Q000494:pharmacology*; D000244:Adenosine Diphosphate / Q000031:analogs & derivatives* / Q000378:metabolism* / Q000494:pharmacology; D000818:Animals; D001013:Aorta, Thoracic / Q000502:physiology*; D002118:Calcium / Q000378:metabolism; D003331:Coronary Vessels / Q000502:physiology; D057809:HEK293 Cells; D006801:Humans; D066298:In Vitro Techniques; D008297:Male; D008638:Mesenteric Arteries / Q000502:physiology; D009126:Muscle Relaxation / Q000187:drug effects; D010171:Palmitoyl Coenzyme A / Q000494:pharmacology; D058921:Purinergic P2Y Receptor Antagonists / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D058472:Receptors, Purinergic P2Y1 / Q000378:metabolism; D013552:Swine; D014530:Uridine Diphosphate / Q000378:metabolism*
chemical_list: D000214:Acyl Coenzyme A; C111914:N(6)-methyl-2'-deoxyadenosine 3',5'-diphosphate; D058921:Purinergic P2Y Receptor Antagonists; D058472:Receptors, Purinergic P2Y1; D010171:Palmitoyl Coenzyme A; D014530:Uridine Diphosphate; D000244:Adenosine Diphosphate; D000105:Acetyl Coenzyme A; D002118:Calcium