Angiographic assessment of human coronary artery endothelial function by measurement of endothelium-dependent vasodilation

In isolated atherosclerotic human coronary arteries endothelium-dependent vascular relaxation is abolished with acetylcholine whereas another EDRF-dependent vasodilator, substance P, still produces significant relaxation. To study further these in vitro findings, graded doses of acetylcholine and substance P, which produced no systemic effects, were infused into the left anterior descending artery of patients with angiographically moderate coronary artery disease. The effects of acetylcholine and substance P on LAD diameter were analysed by quantitative angiography. Generally, acetylcholine caused no relaxation but concentration-dependent contractions from 1·67±0·06mm to 1·45±0·09mm (P