Abstract
We characterized postischemic changes in myocardial metabolism and regional external work, as measured by the integral of left ventricular pressure-segment-length loops. In 12 anesthetized swine, the left anterior descending coronary artery (LAD) was occluded for 10 min and reperfused for 30 min for two successive cycles. Before ischemia, regional work was 16,920 ± 5,630 mmHg-mm/min and after stunning, work was reduced to 50 ± 14% (P < 0.05). At baseline, oxygen and lactate consumption were 4.80 ± 1.40 and 1.02 ± 0.46 μmol·min-1·g-1, respectively, and after stunning they were reduced to 3.24 ± 0.80 (P < 0.05) and 0.16 ± 0.21 μmol·min-1·g-1 (P < 0.05), respectively. The atria were then paced 50 beats/min higher than the reperfusion heart rate, during and without an infusion of dobutamine (2 μg·kg-1·min-1). During dobutamine, both regional external work and oxygen consumption returned to 98% of preischemic values, but lactate utilization remained depressed. We conclude that regional external work and oxygen consumption remain coupled during inotropic stimulation after stunning, with a preferential shift toward nonlactate substrates.
| Original language | English (US) |
|---|---|
| Pages (from-to) | H1724-H1731 |
| Journal | American Journal of Physiology - Heart and Circulatory Physiology |
| Volume | 263 |
| Issue number | 6 32-6 |
| DOIs | |
| State | Published - 1992 |
| Externally published | Yes |
Bibliographical note
Funding Information:This work has been supported by the EU, INFM and MIUR. We thank L. De Sarlo and R. Saers for their active participation in the experimental part of the work and B. Englert and S. Olivares for useful discussions. We also thank J. E. Lye for a careful reading of the manuscript.
Keywords
- dobutamine
- external work
- myocardial stunning
- oxygen consumption