Sevoflurane postconditioning protects the myocardium against ischemia/reperfusion injury via activation of the JAK2-STAT3 pathway

Abstract

Background: Sevoflurane postconditioning (S-post) has similar cardioprotective effects as ischemic preconditioning. However, the underlying mechanism of S-post has not been fully elucidated. Janus kinase signaling transduction/transcription activator (JAK2-STAT3) plays an important role in cardioprotection. The purpose of this study was to determine whether the cardioprotective effects of S-post are associated with activation of the JAK2-STAT3 signal pathway.

Methods: An adult male Sprague-Dawley (SD) rat model of myocardial ischemia/reperfusion (I/R) injury was established using the Langendorff isolated heart perfusion apparatus. At the beginning of reperfusion, 2.4% sevoflurane alone or in combination with AG490 (a JAK2 selective inhibitor) was used as a postconditioning treatment. The cardiac function indicators, myocardial infarct size, lactic dehydrogenase (LDH) release, mitochondrial ultrastructure, mitochondrial reactive oxygen species (ROS) generation rates, ATP content, protein expression of p-JAK, p-STAT3, Bcl-2 and Bax were measured.

Results: Compared with the I/R group, S-post significantly increased the expression of p-JAK, p-STAT3 and Bcl-2 and reduced the protein expression of Bax, which markedly decreased the myocardial infarction areas, improved the cardiac function indicators and the mitochondrial ultrastructure, decreased the mitochondrial ROS and increased the ATP content. However, the cardioprotective effects of S-post were abolished by treatment with a JAK2 selective inhibitor (p < 0.05).

Conclusion: This study demonstrates that the cardioprotective effects of S-post are associated with the activation of JAK2-STAT3. The mechanism may be related to an increased expression of p-JAK2 and p-STAT3 after S-post, which reduced mitochondrial ROS generation and increased mitochondrial ATP content, thereby reducing apoptosis and myocardial infarct size.

Keywords: Apoptosis; Ischemia–reperfusion injury; JAK2–STAT3 pathway; Reactive oxygen species; Sevoflurane postconditioning.

Figure 1. The schematic diagram of the experimental procedures.

I/R, ischemic/reperfusion; S-post, sevoflurane postconditioning; AG490, JAK2 selective inhibitor.

Figure 2. S-post improve myocardial function in vitro model.

Hemodynamic changes were measured at the end of reperfusion (n = 12/group). (A) Heart rate (HR, beat/per min); (B) left ventricular developed pressure (LVDP, mmHg); (C) left ventricular end-diastolic pressure (LVEDP, mmHg); (D) maximum rate of increase of LV pressure (+dp/dt_max, mmHg/s). *p < 0.05 compared with sham group, ^#p < 0.05 compared with I/R group and ^&p < 0.05 compared with S-post group.

Figure 3. S-post reduce myocardial infarct size and LDH release (n = 12/group).

(A) Myocardial infarct size, the infarction zone (white) and risky zone (red). (B) Myocardial infarct size (IS) expressed as the percentage of the infarct area relative to the total at-risk area after 2 h of reperfusion; (C) The LDH release level. *p < 0.05 compared with sham group, ^#p < 0.05 compared with I/R group and ^&p < 0.05 compared with S-post group.

Figure 4. The changes in the levels of p-JAK2, p-STAT3, Bcl-2 and Bax at the end of reperfusion (n = 5/group).

*p < 0.05 compared with sham group, ^#p < 0.05 compared with I/R group and ^&p < 0.05 compared with S-post group.

Figure 5. S-post alleviated mitochondrial ultrastructural damage and improved myocardial energy metabolism.

(A) The changes in the mitochondrial ultrastructural (n = 6/group); (B) Mitochondrial ATP content (n = 6/group). *p < 0.05 compared with sham group, ^#p < 0.05 compared with I/R group and ^&p < 0.05 compared with S-post group.

Figure 6. S-post reduced mitochondrial ROS production.

Mitochondrial ROS production rates (RPR) at the end of reperfusion. Data are presented as the mean ± SEM (n = 6/group). *p < 0.05 compared with sham group, ^#p < 0.05 compared with I/R group and ^&p < 0.05 compared with S-post group.