Intermittent ischemia-reperfusion as a potent insulin-sensitizing intervention via blood flow enhancement and muscle Decanoyl-L-carnitine suppression.

Abstract

A single bout of exercise improves muscle insulin sensitivity for up to 48 hours via the AMP-activated protein kinase (AMPK). Limb ischemia activates AMPK in muscle, and subsequent reperfusion enhances insulin-stimulated vasodilation, potentially eliciting a more pronounced exercise effect with reduced workload. Here, we investigated the combined effect of upper leg intermittent ischemia-reperfusion (IIR) and continuous knee-extension exercise on muscle insulin sensitivity regulation. We found that IIR-exercise potentiated AMPK activation and muscle insulin sensitivity. The potentiating effect of IIR-exercise on muscle insulin sensitivity was associated with increased insulin-stimulated blood flow in parallel with enhanced phosphorylation of endothelial nitric oxide synthase. Metabolomics analyses demonstrated a suppression of muscle medium-chain acylcarnitines during IIR-exercise, which correlated with insulin sensitivity and was consistent with findings in isolated rat muscle treated with Decanoyl-L-carnitine. Collectively, combining IIR with low-to-moderate intensity exercise may represent a promising intervention to effectively enhance muscle insulin sensitivity. This approach could offer potential for mitigating muscle insulin resistance in clinical settings and among individuals with lower physical activity levels.