RELEASE OF ENDOTHELIN FROM THE PORCINE HEART AFTER SHORT-TERM CORONARY-ARTERY OCCLUSION

Objective: Endothelin is increased in plasma following myocardial infa rction. Whether brief periods of myocardial ischaemia not leading to m yocardial infarction increase plasma endothelin is not known. Thus, th e present study was designed to examine cardiac endothelin balance in association with a 10 min coronary artery occlusion followed by reperf usion. Methods: Venous blood was selectively sampled from the transien tly ischaemic myocardium using a shunt between the anterior interventr icular vein and the right atrium in eight pentobarbitone anaesthetised pics. Flow in the shunt was measured with a Doppler flow probe. Arter ial blood was drawn from the aortic arch. Plasma endothelin was measur ed using an Endothelin 1-21 specific [I-125] assay system. This assay system has no cross reactivity with big endothelin. Results: A net car diac endothelin uptake of 0.7(0.3-1.4) fmol.min-1.g-1 (median, 95% con fidence interval) in the control period shifted to a net release durin g the first 10 min of reperfusion. The release reached a maximum of 2. 8(0.4-6.0) fmol.min-1.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, respective ly (p<0.001 for both). Arterial endothelin concentration decreased fro m 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 m inutes during reperfusion following a brief coronary artery occlusion.