Preservation of myofilament calcium responsiveness underlies protection against myocardial stunning by ischemic preconditioning

被引:15
作者
Pérez, NG
Marbán, E
Cingolani, HE
机构
[1] Johns Hopkins Univ, Sch Med, Dept Med, Sect Mol & Cellular Cardiol, Baltimore, MD 21205 USA
[2] UNLP, Fac Ciencias Med, Ctr Invest Cardiovasc, La Plata, Buenos Aires, Argentina
关键词
ischemia; reperfusion; stunning; calcium (cellular); preconditioning;
D O I
10.1016/S0008-6363(98)00299-5
中图分类号
R5 [内科学];
学科分类号
1002 ; 100201 ;
摘要
Objective: Whereas diminution of infarct size by ischemic preconditioning (IP) is well-accepted, protection against stunning is controversial. Since stunning is characterized by decreased myofilament Ca2+ responsiveness, we investigated whether IP would preserve myofilament responsiveness in a model of stunning. Methods: Rat hearts were retrogradely pet-fused with Krebs-Henseleit (K-H) solution for 20 min and then subjected to 20 min of no-flow global ischemia, followed by 20 min of reperfusion in the absence (stunning) or in the presence (IP) of a previous 5-min period of ischemia followed by 15 min of reperfusion. A group of hearts perfused under non-ischemic conditions served as control. Thin ventricular trabeculae were dissected from each of the experimental groups and loaded with fura-2 to measure intracellular calcium concentration ([Ca2+](i)) and developed force. Results: After 20 min of reperfusion, left ventricular developed pressure decreased in stunned hearts to 61+/-5% of control (P<0.01), whereas recovery was complete in the IP hearts (97+/-4%). Steady-state [Ca2+](i)-force relationships revealed a decreased maximal Ca2+-activated force in stunned hearts relative to control, but no change in the IP group. The Ca2+ required for 50% activation increased in stunning but not in IP. Conclusions: These results show that the decrease in myofilament responsiveness that characterizes stunning is prevented by ischemic preconditioning. (C) 1999 Elsevier Science B.V. All rights reserved.
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页码:636 / 643
页数:8
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