Effects of buffered pyruvate on regional cardiac function in moderate, short-term ischemia in swine heart.

Previous studies showed that pyruvate with Tris buffer improves mechanical and metabolic functions of globally ischemic swine hearts. The purpose of the present study was to evaluate their effects during short periods of moderate regional ischemia. Studies were conducted on 21 swine hearts during maintenance of control flow to the anterior descending (LAD) and circumflex (LCf) coronary arteries and through 15 minutes of LAD ischemia (flow reduced from 47.1-19.0 ml/min). Pyruvate at control coronary flows increased systolic and total shortening at the apex (0.24-0.36 mm, P < 0.01, and 0.34-0.47 mm, P < 0.025, respectively) and increased oxygen extraction (O2 EXT) and consumption (MVO2) across both beds (LAD: O2 EXT 36.5-48.6%, P< 0.005; MVO2 106.1-130.7 /imol/min, P< 0.05; LCf: O2 EXT 31.6-43.8%, P < 0.005; MVO2 125.3-159.3 /imol/min, P< 0.025). Pyruvate during LAD ischemia, as compared with untreated myocardium, increased diastolic and total shortening at the apex (0.21-0.25 mm, P < 0.05, and 0.18-0.31 mm, P < 0.05, respectively) and increased global contractility (left ventricular max dp/dt from 2726-3220 mm Hg/sec, P< 0.05). O2 EXT and MVO2 were not further increased in the LAD bed, but glucose utilization, as estimated from the release of H2O from glucose[2-H] infusions, was accelerated (3.93-6.05 /imol/min, P < 0.01). O2 EXT and MVO2 in the LCf circuit during LAD ischemia were significantly increased (42.4-52.7%, P < 0.05, and 169.4-189.7 /imol/min, P < 0.05, respectively). The increases in mechanical function persisted in treated hearts during the immediate postischemic period at 1 and 5 minutes of reflow. Thus, buffered pyruvate effected significant improvements in regional motion both at control and ischemic coronary flows in working swine hearts and was associated with increases both in aerobic and anaerobic metabolism.