AJP - Heart and Circulatory Physiology, Vol 241, Issue 4 591-H599, Copyright © 1981 by American Physiological Society
Prolonged abnormalities of myocardium salvaged by reperfusion
R. A. Kloner, L. W. DeBoer, J. R. Darsee, J. S. Ingwall, S. Hale, J. Tumas and E. Braunwald
The purpose of this study was to determine if biochemical, functional, and
ultrastructural abnormalities persist in nonnecrotic postischemic
myocardium salvaged by coronary reperfusion. Anesthetized dogs were
subjected to 15 min of occlusion of the left anterior descending (LAD)
coronary artery followed by 3 days of reperfusion. Biopsies were obtained
for measurement of adenosine 5'-triphosphate (ATP) and creatine phosphate
(CP) nmol/mg protein), and regional function was evaluated using
sonomicrometry. Myocardial ATP concentration after 15 min of occlusion was
37 +/- 1 nmol/mg cardiac protein in nonischemic subendocardium and 19 +/- 2
nmol/mg in ischemic subendocardium. After the hearts underwent 90 min and
72 h of reperfusion, ATP remained significantly depressed in reperfused
subendocardium with values of 25 +/- 5 and 29 +/- 2 nmol/mg, respectively
(P less than 0.05 and P less than 0.01 compared with the nonischemic zone
in which ATP remained normal). CP levels fell during ischemia but returned
to normal by 90 min of reperfusion. Percent systolic shortening of
myocardial segments fell from +18 +/- 1% (active shortening) to -13 +/- 2%
(passive lengthening) during ischemia and was still significantly depressed
at +11 +/- 1% (P less than 0.05 vs. preocclusion) at 72 h of reperfusion.
Histological examination showed no necrosis, but ultrastructural
abnormalities were present. Therefore brief periods of myocardial ischemia
are not associated with necrosis but result in functional, biochemical, and
ultrastructural abnormalities, which are present for at lest 3 days after
coronary reperfusion.
