Carnosine Supplementation Enhances Post Ischemic Hind Limb Revascularization.

High (millimolar) concentrations of the histidine containing dipeptide - carnosine (beta-alanine-L-histidine) are present in the skeletal muscle. The dipeptide has been shown to buffer intracellular pH, chelate transition metals, and scavenge lipid peroxidation products; however, its role in protecting against tissue injury remains unclear. In this study, we tested the hypothesis that carnosine protects against post ischemia by augmenting HIF-1a angiogenic signaling by Fe2+ chelation. We found that wild type (WT) C57BL/6 mice, subjected to hind limb ischemia (HLI) and supplemented with carnosine (1g/L) in drinking water, had improved blood flow recovery and limb function, enhanced revascularization and regeneration of myocytes compared with HLI mice placed on water alone. Carnosine supplementation enhanced the bioavailability of carnosine in the ischemic limb, which was accompanied by increased expression of proton-coupled oligopeptide transporters. Consistent with our hypothesis, carnosine supplementation augmented HIF-1 alpha and VEGF expression in the ischemic limb and the mobilization of proangiogenic Flk-1(+)/Sca-1(+) cells into circulation. Pretreatment of murine myoblast (C2C12) cells with octyl-D-carnosine or carnosine enhanced HIF-1 alpha protein expression, VEGF mRNA levels and VEGF release under hypoxic conditions. Similarly pretreatment of WT C57/B16 mice with carnosine showed enhanced blood flow in the ischemic limb following HLI surgery. In contrast, pretreatment of hypoxic C2C12 cells with methylcarcinine, a carnosine analog, lacking Fe2+ chelating capacity, had no effect on HIF-1a levels and VEGF release. Collectively, these data suggest that carnosine promotes post ischemic revascularization via augmentation of pro-angiogenic HIF-1 alpha/VEGF signaling, possibly by Fe2+ chelation.