To investigate the possible role of endothelin in coronary vasoconstriction contributing to the development of myocardial ischemia, plasma endothelin concentrations at rest and during atrial pacing-induced myocardial ischemia have been measured in blood samples drawn from the aorta and coronary sinus in 12 patients with significant narrowing of the left anterior descending coronary artery. The plasma endothelin concentrations at rest were similar in the aorta (AO/R) and coronary sinus (CS/R) (4.8 +/- 2.4 and 4.5 +/- 1.7 pg/ml, respectively), the difference between coronary sinus and aorta plasma endothelin concentration (CS/R-AO/R) being -0.3 +/- 1.7 pg/ml. During atrial pacing-induced myocardial ischemia aortic plasma endothelin concentration (AO/P) did not change (4.6 +/- 2.6 pg/ml) and only an insignificant increase in the plasma endothelin concentration in the coronary sinus (CS/P) was observed (5.3 +/- 2.8 pg/ml). The difference between coronary sinus and aortic endothelin plasma concentration (CS/P-AO/P) was 0.6 +/- 2.5 pg/ml. Finally, the difference in endothelin concentrations between coronary sinus and aorta rose only insignificantly during pacing as compared to the resting values ([CS/P-AO/P]-[CS/R-AP/R] being 0.9 +/- 3.2 pg/ml). Thus, atrial pacing-induced myocardial ischemia in patients with significant left anterior descending coronary artery stenosis was not accompanied by significant changes in coronary sinus plasma endothelin concentrations.(ABSTRACT TRUNCATED AT 250 WORDS)

Department of Medicine 2 1st Medical Faculty Charles University Prague Czech Republic

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