1. Attenuation of ST-segment elevation by ischemic preconditioning: Reflection of cardioprotection in Göttingen but not in Ossabaw minipigs.
- Author
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Lieder, Helmut Raphael, Adam, Virginie, Skyschally, Andreas, Sturek, Michael, Kleinbongard, Petra, and Heusch, Gerd
- Subjects
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ISCHEMIC preconditioning , *CORONARY occlusion , *MYOCARDIAL infarction , *CELLULAR signal transduction , *METABOLIC syndrome - Abstract
Ischemic preconditioning (IPC; brief cycles of coronary occlusion/ reperfusion) reduces myocardial infarct size. The ST-segment elevation during coronary occlusion is progressively attenuated with increasing number of IPC cycles. Progressive attenuation of ST-segment elevation is considered a result of sarcolemmal K ATP channel activation and has been considered to reflect and predict IPC's cardioprotection. We have recently demonstrated that IPC failed to reduce infarct size in minipigs of a particular strain (Ossabaw), which had a genetic predisposition to develop, but not yet established a metabolic syndrome. To determine whether or not Ossabaw minipigs nevertheless had attenuated ST-segment elevation over repetitive IPC cycles, we compared Göttingen vs. Ossabaw minipigs in which IPC reduces infarct size. We analyzed surface chest electrocardiographic (ECG) recordings of anesthetized open-chest contemporary Göttingen (n = 43) and Ossabaw minipigs (n = 53). Both minipig strains were subjected to 60 min coronary occlusion and 180 min reperfusion without or with IPC (3 × 5 min/ 10 min coronary occlusion/ reperfusion). ST-segment elevations during the repetitive coronary occlusions were analyzed. In both minipig strains, IPC attenuated ST-segment elevation with increasing number of coronary occlusions. IPC reduced infarct size in Göttingen minipigs (45 ± 10% without vs. 25 ± 13% of area at risk with IPC), whereas such cardioprotection was absent in Ossabaw minipigs (54 ± 11% vs. 50 ± 11%). Apparently, the block of signal transduction of IPC in Ossabaw minipigs occurs distal to the sarcolemma, where K ATP channel activation still attenuates ST-segment elevation as it does in Göttingen minipigs. [Display omitted] • Progressive attenuation of ST-segment elevation with repetitive coronary occlusions reflects cardioprotection by ischemic preconditioning (IPC) and is attributed to sarcolemmal K ATP channel activation. • IPC does not reduce infarct size in Ossabaw minipigs, in contrast to the established infarct size reduction in Göttingen minipigs. • Progressive attenuation of ST-segment elevation with repetitive coronary occlusions occurs in both strains. • The block of cardioprotective IPC signaling in Ossabaw minipigs occurs distal to the sarcolemma. • Progressive attenuation of ST-segment elevation with repetitive coronary occlusions is an unreliable reflection of cardioprotection. [ABSTRACT FROM AUTHOR]
- Published
- 2023
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