Adenosine-supplemented blood cardioplegia attenuates postischemic dysfunction after severe regional ischemia

Background - Various studies have reported that the administration of adeno sine (ADO) in cardioplegia reduces myocardial ischemic injury, but this tim ing may not utilize ADO's potential against myocardial reperfusion injury. This study tested the hypothesis that ADO-supplemented blood cardioplegia ( BCP) or ADO administered during reperfusion reduces postischemic dysfunctio n after severe regional ischemia. Methods and Results - After 75 minutes of left anterior descending coronary artery occlusion, total cardiopulmonary bypass was initiated; cold (4 degr ees C) antegrade BCP (8:1 blood:crystalloid) was delivered every 20 minutes for the first 3 doses, and 27 degrees C BCP was delivered for the terminal infusion. Dogs (n = 6 per group) received unsupplemented BCP, ADO (100 mu mo/L/L) supplemented in all infusions of BCP (ADO-CP), or ADO (100 mu mol . L-1 . L-1) supplemented only in the terminal infusion of BCP followed by i ntravenous ADO (140 mu g . kg(-1) . min(-1)) infusion for the first 30 minu tes of reperfusion (ADO-R). Postischemic regional systolic shortening was s ignificantly greater in the ADO-R group (5 +/- 2.0%) than in the BCP group (-3 +/- 1.0%), but not in the ADO-CP group (2 +/- 0.2%). Postischemic regio nal diastolic stiffness in the area at risk during end reperfusion was lowe r with ADO-R (1.8 +/- 0.3%) than with ADO-CP (2.7 +/- 0.3%) or BCP (4.4 +/- 0.5%). Infarct size was reduced in the ADO-CP (29 +/- 2%) and ADO-R (21 +/ - 2%) groups compared with the BCP group (42 +/- 4%). Edema in the myocardi al area at risk was decreased in the ADO-CP (82 +/- 0.2%) and ADO-R (80 +/- 0.4%) groups compared with the BCP group (86 +/- 0.7%). Adherence of fluor escently labeled neutrophils (PMNs) to postischemic coronary artery endothe lium was attenuated by ADO-R (55 +/- 2. PMNs/ mm(2)), but not by ADO-CP (11 4 +/- 5 PMNs/mm(2)), compared with BCP (118 +/- 3 PMNs/mm(2)). Conclusions - The results show that BCP supplemented with ADO reduces infar ct size, preserves postischemic systolic and diastolic regional function bu t does not attenuate coronary artery endothelial dysfunction unless adminis tered during reperfusion.