Endothelin-1 (ET-1) is an endothelium-derived mediator with vasoconstrictive and mitogenic activity which stimulates vascular smooth muscle cell proliferation. The aim of this study was to evaluate ET-1 production during percutaneous transluminal coronary angioplasty (PTCA) and elective stent implantation. We hypothesized that the additional vessel wall trauma induced by stent deployment might be associated with a greater production of ET-1. To this end, ET-1 levels were measured in 18 patients undergoing PTCA and stenting (12 with left anterior descending coronary artery stenosis and 6 with circumflex artery lesion). The sampling sites were the coronary ostium and coronary sinus in basal conditions (before the procedure), during first balloon inflation, and 5, 20, 60 min after the end of first balloon inflation. At baseline, ET-1 levels were higher in the coronary sinus than in coronary ostium (1.58 +/- 0.22 vs 1.29 +/- 0.20 pg/ml, p < 0.001). During first balloon inflation, ET-1 coronary sinus levels significantly diminished with respect to the basal levels (1.08 +/- 0.32 vs 1.58 +/- 0.22 pg/ml, p < 0.001). Further significant variations of ET-1 levels were not detected neither following the first balloon inflation nor after stent deployment. In conclusion, the culprit lesion seems to produce most of ET-1 circulating in the coronary tree. This is demonstrated by higher ET-1 levels in the coronary sinus compared to coronary ostium at baseline, and even more by the significant ET-1 reduction in the coronary sinus during first balloon inflation. Despite our expectations, we did not detect any significant ET-1 increase during stent deployment.