INCREASED PLASMA-LEVEL OF ENDOTHELIN-1-LIKE IMMUNOREACTIVITY DURING CORONARY SPASM IN PATIENTS WITH CORONARY SPASTIC ANGINA

To examine the role of endothelin in coronary spasm, the plasma endothelin-1-like immunoreactivity in the coronary sinus and the aortic root was measured before and during spasm of the left coronary artery induced by injection of acetylcholine (20 to 100-mu-g) into the left coronary artery in 26 patients with coronary spastic angina. The plasma level of endothelin-1-like immunoreactivity was measured by the radioimmunoassay with a monoclonal antibody against endothelin-1. Plasma lactate levels in the coronary sinus and the aortic root were also measured to evaluate myocardial lactate metabolism during spasm. In 13 patients who had myocardial lactate production during spasm, the plasma level of endothelin-1-like immunoreactivity in the coronary sinus increased from 19.8 +/- 3.0 to 25.7 +/-6.4 pg/ml (p < 0.01), while that in the aortic root remained unchanged (from 20.2 +/- 5.9 to 21.3 +/-5.8 pg/ml). No significant changes in the plasma levels of endothelin-1-like immunoreactivity in the coronary sinus (from 21.1 +/- 7.3 to 19.7 +/-5.2 pg/ml) and the aortic root (from 21.1 +/- 5.7 to 19.7 +/- 5.6 pg/ml) were observed in 13 patients who did not show myocardial lactate production during spasm. On the other hand, 16 patients without ischemic heart disease showed no significant changes in the plasma levels of endothelin-1-like immunoreactivity in the coronary sinus (from 24.4 +/- 9.7 to 25.8 +/- 6.9 pg/ml) and the aortic root (from 23.0 +/- 7.1 to 23.4 +/- 5.8 pg/ml) by acetylcholine injection (100-mu-g). These results indicate that endothelin is released into the coronary circulation in response to coronary spasm with metabolic evidence of myocardial ischemia.