Coronary sinus adrenomedullin rises in response to myocardial injury

Human adrenomedullin (ADM), a peptide comprising 52 amino acids, is a circu lating hormone with vasodilator properties. We have evaluated ifs release b y the heart following ischaemic myocardial damage, as indicated by elevated levels of the cardiospecific protein troponin-T (Tn-T) during cardiopulmon ary bypass. ADM (pg/ml) and Tn-T (ng/ml) were measured in coronary sinus bl ood before and after aortic cross-clamp and in venous blood 6 h after surge ry in 22 coronary-bypass patients. Based on the pre- and post-clamp Tn-T le vels in the coronary sinus, the patients were divided into group I (no chan ge; n = 10) and group II (two times increase; n = 12). Baseline ADM (362.7 +/- 106.2 and 303 +/- 58.7 pg/ml in groups I and II respectively; means +/- S.D.) and Tn-T (0.66+/-0.14 and 0.57+/-0.13 ng/ml respectively) levels wer e similar in both groups. In group I, the post-clamp ADM (317.6+/-80.8 pg/m l) and Tn-T (0.68+/-0.15 ng/ml) levels did not change significantly. In gro up II, the post-clamp ADM levels rose significantly above the baseline, mim icking the change in Tn-T (ADM, 541.4+/-89.4 pg/ml; Tn-T, 1.37+/-0.31 ng/ml ; P = 0.009). After 6 h, the systemic Tn-T levels were similar in both grou ps (2.09+/-0.44 and 1.95/-0.52 ng/ml in groups I and II respectively). We s uggest that: (I) minor degrees of myocardial ischaemic damage result in rel ease of ADM by the heart, and (2) ADM may play a protective role in the myo cardium during an ischaemic insult. This suggests a possible therapeutic ro le for ADM in the management of intra-operative myocardial ischaemia.