Objective: Endothelin is increased in plasma following myocardial infarction. Whether brief periods of myocardial ischaemia not leading to myocardial infarction increase plasma endothelin is not known. Thus, the present study was designed to examine cardiac endothelin balance in association with a 10 min coronary artery occlusion followed by reperfusion.
Methods: Venous blood was selectively sampled from the transiently ischaemic myocardium using a shunt between the anterior interventricular vein and the right atrium in eight pentobarbitone anaesthetised pigs. Flow in the shunt was measured with a Doppler flow probe. Arterial blood was drawn from the aortic arch. Plasma endothelin was measured using an Endothelin 1-21 specific [125I] assay system. This assay system has no cross reactivity with big endothlin.
Results: A net cardiac endothelin uptake of 0.7(0.3-1.4) fmol.min-1 x g-1 (median, 95% confidence interval) in the control period shifted to a net release during the first 10 min of reperfusion. The release reached a maximum of 2.8(0.4-6.0) fmol.min-1 x g-1 after 1.5 min of reperfusion. Cardiac venous endothelin concentration increased from 3.4(2.5-4.8) to 4.4(3.6-6.9) and 4.4(3.6-6.6) fmol.ml-1 at 1.5 and 5 min of reperfusion, respectively (p < 0.001 for both). Arterial endothelin concentration decreased from 4.8(3.9-6.1) to 2.7(2.4-4.3) fmol.ml-1 at 10 min of reperfusion (p < 0.001).
Conclusion: Endothelin is released from the heart for several minutes during reperfusion following a brief coronary artery occlusion.