Coronary vasomotor responses to bradykinin and acetylcholine in patients with coronary spastic angina

It is unclear whether coronary endothelial function is linked to the pathog enesis of coronary spastic angina (CSA), so the present study examined the coronary vasomotor responses to acetylcholine (ACh) and bradykinin (BK) in 23 patients with CSA. 26 patients with CSA+coronary artery disease (CAD), a nd 21 control patients. Acetylcholine induced vasospasm of the left coronar y artery in all of the patients with CSA, but not in any of the control pat ients. The changes in dilatation of the left coronary artery in response to bradykinin at doses of 0.2, 0.6 and 2.0 mug/min in the CSA group were sign ificantly greater than those in the other 2 groups. The ratio of epicardial coronary vasodilations induced by BK to those induced by nitroglycerin did not differ among any of the groups. Bradykinin caused a similar increase i n coronary blood flow in the control group and CSA group, but had less of a n effect in the CSA+CAD group. In conclusion, the vasorelaxing effect of BK was preserved not only in epicardial spasm coronary arteries induced by AC h, but also in resistance coronary arteries distal to the spasm arteries in patients with CSA. The coronary vasodilation response induced by BK may no t deteriorate until coronary atherosclerosis advances in patients with CSA.