Author + information
- Received September 2, 1986
- Revision received February 26, 1987
- Accepted March 26, 1987
- Published online September 1, 1987.
- ↵†Address for reprints: Brian D. Guth, PhD, Department of Medicine, A-011. University of California, San Diego, La Jolla. California 92093.
Postreperfusion regional myocardial dysfunction may be associated with depletion of high energy phosphate compounds during ischemia and with their relatively slow repletion during reperfusion. However, few studies have correlated relatively rapid changes in regional myocardial function (sonomicrometers) and blood flow (microspheres) with high energy phosphate concentrations measured using phosphorus-31 nuclear magnetic resonance spectroscopy in intact large animal models of regional myocardial ischemia. The left anterior descending coronary artery of mongrel dogs was abruptly occluded for 17.1 ± 1.9 minutes and then completely released; measurements were made for an additional 22 minutes. Transmural blood flow decreased from 1.07 ± 0.25 to 0.25 ± 0.10 ml/(min × g) and holosystolic expansion was observed in all dogs (segmental systolic shortening decreased from 9.3 ± 3.7 to −6.3 ± 6.0%). Phosphocreatine (PCr) measured during 4.4 minute sampling intervals decreased to steady state within the first sampling period after occlusion and was 45.9 ± 17.0% of control at the end of the occlusion, whereas beta-adenosine triphosphate (beta-ATP) reached its lowest level early after reperfusion (72.7 ± 13.3% of control). The ratio of PCr to inorganic phosphate (Pi) decreased during the occlusion (3.34 ± 0.75 versus 1.01 ± 0.61) but returned to control level early during reperfusion. The ratio of PCr to beta-ATP also decreased during coronary occlusion (2.16 ± 0.39 versus 1.29 ± 0.39) but did not return to control level during reperfusion.
Significant correlations were observed between the intensity of ischemia (reduced blood flow) and reductions in regional contractile function, PCr, beta-ATP, myocardial pH and the increase in Pi during the coronary occlusion. Also during ischemia, there were significant correlations between regional contractile function and both myocardial pH and Pi. PCr returned to control level rapidly after reperfusion (95.9 ± 13.2% of control in less than 5 minutes of reperfusion) whereas beta-ATP recovered only partially after 22 minutes (80.0 ± 17.5% of control). The correlation between the fraction of control beta-ATP and the fraction of control regional function at this time was r = 0.84 (p = 0.017).
These results demonstrate metabolic correlates to regional myocardial ischemia in an intact dog model using phosphorus-31 spectroscopy. Additionally during reperfusion, beta-ATP, but not PCr, could be associated with the recovery of regional segmental contractile function.
- Received September 2, 1986.
- Revision received February 26, 1987.
- Accepted March 26, 1987.
- American College of Cardiology Foundation