C-reactive protein-induced in vitro vasorelaxation is an artefact caused by the presence of sodium azide in commercial preparations.
OBJECTIVE
Although C-reactive protein (CRP) is increasingly recognized as an independent risk factor for acute myocardial events, recent evidence suggests that it can directly induce vasorelaxation. This study aimed to investigate the mechanism of this CRP-induced response.


RESULTS
Isometric tension recordings were used to measure endothelium-dependent and endothelium-independent vascular smooth muscle relaxation in isolated rabbit aortic rings. CRP generated in-house by genetic engineering and expressed in Chinese hamster ovary cells, CRP purified from ascites, and CRP obtained from commercial sources were assessed for vasorelaxing properties. Only the commercial CRP preparation induced vasorelaxation; more than half maximal relaxation was observed at 0.025 microg/mL and maximum relaxation attained at 0.25 microg/mL. Commercial CRP contains high levels of sodium azide, a well-known vasorelaxant. Removal of this agent by dialysis abolished the vasodilatory effect of commercial CRP. Sodium azide alone at concentrations equivalent to that present in the commercial CRP produced a near-identical relaxation pattern to the undialyzed commercial product.


CONCLUSIONS
CRP has no vasorelaxant properties per se, and the reported vasorelaxant ability of CRP is an artifact caused by sodium azide present in commercial preparations of this agent.
van den Berg
Carmen W
CW
Department of Pharmacology, Therapeutics, and Toxicology, Wales Heart Research Institute, University of Wales College of Medicine, Heath Park, Cardiff, CF14 4XN, United Kingdom. vandenbergcw@cardiff.ac.uk.
Taylor
Karolina E
KE
Lang
Derek
D
D000818:Animals; D001013:Aorta, Thoracic / Q000187:drug effects; D016477:Artifacts; D001202:Ascitic Fluid / Q000737:chemistry; D002097:C-Reactive Protein / Q000737:chemistry* / Q000494:pharmacology*; D016466:CHO Cells / Q000737:chemistry / Q000378:metabolism; D006224:Cricetinae; D006801:Humans; D066298:In Vitro Techniques; D008297:Male; D004364:Pharmaceutical Preparations / Q000737:chemistry*; D011817:Rabbits; D011994:Recombinant Proteins / Q000494:pharmacology; D019810:Sodium Azide / Q000494:pharmacology*; D014664:Vasodilation / Q000187:drug effects*
D004364:Pharmaceutical Preparations; D011994:Recombinant Proteins; D002097:C-Reactive Protein; D019810:Sodium Azide