TY - JOUR
T1 - Alterations in cardiac sarcoplasmic reticulum calcium transport in the postischemic 'stunned' myocardium
AU - Krause, S. M.
AU - Jacobus, W. E.
AU - Becker, L. C.
PY - 1989
Y1 - 1989
N2 - This study examined the possibility that the postischemic mechanical depression observed in the 'stunned' myocardium is a result of an alteration in the control of intracellular calcium. Regional myocardial stunning was produced in five open-chest dogs by eight to twelve 5-minute occlusions of the left anterior descending coronary artery, alternated with 10-minute reflow periods and followed by a final 60-minute period of reperfusion. Systolic segment shortening in the postischemic zone, measured by sonomicrometry, fell from 14.9% at baseline to -1.1% at the end of reperfusion. Sarcoplasmic reticulum isolated from stunned myocardium demonstrated a 17% reduction in oxalate-supported 45Ca2+ transport compared with sarcoplasmic reticulum from normal myocardium (0.93 vs. 1.12 μmol Ca2+/mg protein/min, p < 0.005). There was also a 20% decrease in the maximal activation by Ca2+ of the sarcoplasmic reticulum Ca2+,Mg2+-ATPase (2.46 vs. 1.96 μmol P(i)/mg protein/min, p < 0.005), and a downward shift in the Ca2+-activation curve of the Ca2+,Mg2+-ATPase. These results indicate that myocardial stunning is associated with damage to the calcium-transport system of the sarcoplasmic reticulum. Altered intracellular control may contribute to the inabillity of the stunned heart to maintain normal mechanical function.
AB - This study examined the possibility that the postischemic mechanical depression observed in the 'stunned' myocardium is a result of an alteration in the control of intracellular calcium. Regional myocardial stunning was produced in five open-chest dogs by eight to twelve 5-minute occlusions of the left anterior descending coronary artery, alternated with 10-minute reflow periods and followed by a final 60-minute period of reperfusion. Systolic segment shortening in the postischemic zone, measured by sonomicrometry, fell from 14.9% at baseline to -1.1% at the end of reperfusion. Sarcoplasmic reticulum isolated from stunned myocardium demonstrated a 17% reduction in oxalate-supported 45Ca2+ transport compared with sarcoplasmic reticulum from normal myocardium (0.93 vs. 1.12 μmol Ca2+/mg protein/min, p < 0.005). There was also a 20% decrease in the maximal activation by Ca2+ of the sarcoplasmic reticulum Ca2+,Mg2+-ATPase (2.46 vs. 1.96 μmol P(i)/mg protein/min, p < 0.005), and a downward shift in the Ca2+-activation curve of the Ca2+,Mg2+-ATPase. These results indicate that myocardial stunning is associated with damage to the calcium-transport system of the sarcoplasmic reticulum. Altered intracellular control may contribute to the inabillity of the stunned heart to maintain normal mechanical function.
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U2 - 10.1161/01.RES.65.2.526
DO - 10.1161/01.RES.65.2.526
M3 - Article
C2 - 2752555
AN - SCOPUS:0024320573
SN - 0009-7330
VL - 65
SP - 526
EP - 530
JO - Circulation research
JF - Circulation research
IS - 2
ER -