Storage of radial artery grafts in blood increases vessel reactivity to vasoconstrictors in vitro

Background. Although prone to spasm, the radial artery (RA) is commonly used as a graft in coronary artery bypass surgery (CABG). Successful use of the RA as a graft is dependent on techniques to manage vasospasm during operation. We routinely store the RA in a papaverine blood solution after harvesting, a procedure which might damage the endothelium and predispose the RA to postoperative spasm. The aim of the present study was to evaluate the vasodilator and vasoconstrictor responsiveness in freshly obtained and stored segments of RA. Methods. Discarded segments of RA were obtained at operation from patients undergoing CABG and mounted as 3-mm rings in organ baths for isometric recording of changes in smooth muscle force production. Responses to cumulative additions of acetylcholine, noradrenaline, serotonin, angiotensin II, and the thromboxane A2 mimetic U46619 were normalized to contractions induced by a high potassium solution. Results. Endothelium-dependent relaxation to acetylcholine was not different between preparations from freshly-obtained and blood-stored RA segments. However, maximum contractions to all vasoconstrictors studied were markedly increased in preparations from stored arteries. The sensitivity (pEC50) of stored arteries to U46619, noradrenaline, and angiotensin were also enhanced when compared to preparations from freshly-obtained segments. Conclusions. Papaverine blood solutions do not damage the endothelium of the RA. The observed heightened vasoconstrictor reactivity of stored arteries, most likely mediated by elements of the blood, indicates that asangineous storage solutions should be explored.