Author + information
- Received October 2, 1984
- Revision received February 5, 1985
- Accepted March 14, 1985
- Published online August 1, 1985.
- Markus Schwaiger, MDa,
- Heinrich R. Schelbert, MD, FACC,
- Randy Keen, MSc,
- Jacob Vinten-Johansen, PhD,
- Herbert Hansen, BA,
- Carl Selin, MS,
- Jorge Barrio, PhD,
- Sung-Cheng Huang, DSc and
- Michael E. Phelps, PhD
- ↵aAddress for reprints: Markus Schwaiger, MD, Division of Nuclear Medicine, UCLA School of Medicine, Los Angeles, California 90024.
Free fatty acids are the major energy source for cardiac muscle. Oxidation of fatty acid decreases or even ceases during ischemia. Its recovery after transient ischemia remains largely unexplored. Using intracoronary carbon-11 palmitic acid as a tracer of myocardial fatty acid metabolism in an open chest dog model, retention and clearance of tracer in myocardium were evaluated at control, during ischemia and after reperfusion following a 20 minute occlusion of the left anterior descending coronary artery. Myocardial C-11 time-activity curves were analyzed with biexponential curve-fitting routines yielding fractional distribution and clearance half-times of C-11 palmitic acid in myocardial tissue.
In animals with permanent occlusion and intracoronary injection of C-11 palmitic acid distal to the occlusion site, the relative size and half-time of the early clearance curve component differed markedly from control values and did not change with ongoing ischemia. Conversely, in animals with only 20 minutes of coronary occlusion, the relative size of the early C-11 clearance phase was still significantly depressed at 20 and 90 minutes of reperfusion but returned to control level at 180 minutes. Tissue C-11 clearance half-times remained significantly prolonged throughout the reperfusion period. Regional function in reperfused myocardium monitored with ultrasonic crystals recovered slowly and was still less than control after 3 hours of reperfusion.
The data indicate that after transient ischemia, myocardial fatty acid metabolism fails to recover immediately. Because the metabolic recovery occurs in parallel with recovery of regional function, C-11 palmitic acid in conjunction with positron tomography may be useful for studying regional fatty acid metabolism noninvasively after an ischemic injury, and may be helpful in identifying reversible tissue injury.
This study was supported in part by DOE Contract DE-AC03-76-SF-00012 between the U.S. Department of Energy, Washington, D.C. and the University of California at Los Angeles; by the National Heart, Lung, and Blood Institute, Bethesda, Mary and, Grant HL 29845; and by an Investigative Group Award by the Greater Los Angeles Affiliate of the American Heart Association, Los Angeles, California. The study was presented in part at the 54th Scientific Sessions of the American Heart Association, Dallas, Texas, November 1982.
- Received October 2, 1984.
- Revision received February 5, 1985.
- Accepted March 14, 1985.
- American College of Cardiology Foundation