Key Takeaways & Executive Findings
- •• Protein kinase C differentially regulates Kir6.2 and SUR2A expression in early vs. late exercise preconditioning. • Inhibition of protein kinase C alters mRNA and protein levels of SarcKATP channel subunits in a phase-specific manner. • The regulatory effects of protein kinase C on Kir6.2 and SUR2A are coordinated and complementary across early and late preconditioning. • These findings provide insights into the molecular mechanisms underlying exercise-induced cardioprotection.
Abstract
BACKGROUND: Exercise preconditioning produces early and late myocardial protective effects, in which protein kinase C and myocardial ATP-sensitive potassium channels (SarcKATP) are mediators and effectors, respectively. Protein kinase C regulates the expression of myocardial SarcKATP channels. OBJECTIVE: To compare the effects of protein kinase C on the expression of myocardial SarcKATP channel subunits, inward recirculating potassium channel 6.2 (Kir6.2) and sulfonylurea receptor 2A (SUR2A), in exercise preconditioning. METHODS: Forty-eight Sprague-Dawley rats were randomly divided into five groups: control group (no intervention), early exercise preconditioning group, protein kinase C inhibitor (pre-exercise intraperitoneal injection) + early exercise preconditioning group, late exercise preconditioning group, and protein kinase C inhibitor + late exercise preconditioning group. After preconditioning, the distribution and expression changes of Kir6.2 and SUR2A mRNAs in the rat myocardium were observed and detected using real-time fluorescent quantitative PCR. The distribution and expression changes of Kir6.2 and SUR2A proteins were observed and detected using western blot. RESULTS AND CONCLUSION: (1) Compared with the control group, the mRNA expression of Kir6.2 and SUR2A showed no significant difference in the early and late exercise preconditioning group. (2) Compared with the early exercise preconditioning group, the protein kinase C inhibitor + early exercise preconditioning group showed decreased Kir6.2 mRNA expression but increased Kir6.2 protein expression; both SUR2A mRNA and protein expression decreased. (3) Compared with the late exercise preconditioning group, the protein kinase C inhibitor + late exercise preconditioning group showed decreased Kir6.2 mRNA and SUR2A mRNA expression, decreased Kir6.2 protein expression, but increased SUR2A protein expression. (4) These results indicate that for the same subunit (Kir6.2 or SUR2A), protein kinase C exerts coordinated and complementary regulatory effects in early and late exercise preconditioning; for different subunits (Kir6.2 and SUR2A), protein kinase C also exerts coordinated and complementary regulatory effects on their expression in early and late exercise preconditioning.
1. Introduction
Cardiovascular disease is a leading cause of increased mortality worldwide [1]. Ischemic preconditioning effectively reduces myocardial infarction, ischemia/reperfusion injury, and accelerates heart rate recovery [2-3]. Exercise preconditioning, as a form of exercise intervention, although different from ischemic preconditioning, can produce similar effects. Exercise preconditioning-induced myocardial protection is divided into two phases: early and late exercise preconditioning [4-5]. Exploring the mechanisms underlying exercise preconditioning-induced cardioprotection has been a research hotspot. Studies have found that protein kinase C can influence the cardioprotective effects of both early and late exercise preconditioning [6-7].
Furthermore, exercise preconditioning, as an effective exercise intervention to reduce myocardial ischemia/reperfusion injury, may exert its cardioprotective effects through the mediation of sarcolemmal ATP-sensitive potassium channels (SarcKATP channels) [8]. Further research has shown that protein kinase C can regulate the expression of myocardial SarcKATP channels and their subunits, including inward rectifier potassium channel 6.2 (Kir6.2) and sulfonylurea receptor 2A (SUR2A), thereby inducing cardioprotection [9]. Recent studies have also found that changes in Kir6.2 and SUR2A expression can influence the cardioprotective effects of exercise preconditioning [10-11], and protein kinase C can regulate the expression of myocardial Kir6.2 and SUR2A [11].
Although studies have been conducted on the relationship between protein kinase C and myocardial SarcKATP channels and their roles in inducing cardioprotection, comparative studies on the effects of protein kinase C on the expression of Kir6.2 and SUR2A subunits during different phases of exercise preconditioning have not been reported. This study aims to compare and analyze the effects of protein kinase C, as a mediator, on the expression of myocardial Kir6.2 and SUR2A in early and late exercise preconditioning.
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Wang Kai, Zhou Yuehui (2026). Effects of protein kinase C on the expression of myocardial SarcKATP channels in model rats during exercise preconditioning. Chinese Journal of Tissue Engineering Research. https://doi.org/10.12307/2026.21240
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Frequently Asked Questions
What is the role of protein kinase C in exercise preconditioning?
Protein kinase C acts as a mediator in exercise preconditioning, regulating the expression of myocardial SarcKATP channel subunits (Kir6.2 and SUR2A) to induce cardioprotective effects.
How does protein kinase C affect Kir6.2 and SUR2A expression in early vs. late exercise preconditioning?
In early exercise preconditioning, inhibition of protein kinase C decreases Kir6.2 mRNA but increases Kir6.2 protein, while decreasing both SUR2A mRNA and protein. In late exercise preconditioning, inhibition decreases both Kir6.2 and SUR2A mRNA, decreases Kir6.2 protein, but increases SUR2A protein.
What are the key findings of this study?
The study demonstrates that protein kinase C exerts coordinated and complementary regulatory effects on Kir6.2 and SUR2A expression across early and late exercise preconditioning, providing insights into the molecular mechanisms of exercise-induced cardioprotection.
What methods were used in this study?
The study used real-time fluorescent quantitative PCR to measure mRNA expression and western blot to measure protein expression of Kir6.2 and SUR2A in rat myocardium after exercise preconditioning with or without a protein kinase C inhibitor.
What is the significance of this research?
This research helps clarify the differential regulation of SarcKATP channel subunits by protein kinase C during different phases of exercise preconditioning, which may inform therapeutic strategies for cardiovascular protection.
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