Influence Of Local Muscle Cooling On Mitochondrial Related Gene Expression At Rest

Abstract

Our lab has demonstrated physiological and molecular differences between exercising in ambient cold and an application of local cold. Local cold application has been shown to decrease the temperature of the skin and muscle, causing vasoconstriction, and decreasing blood flow. Currently, the effects of local cold application independent of exercise on mitochondrial related gene expression is unknown. PURPOSE: To determine the impact of localized cooling to the skeletal muscle during rest. METHODS: Thermal wraps were applied to the vastus lateralis (VL) of each limb of 12 participants. One limb received a cold application (randomized) in the form of circulated 10 °C fluid (COLD), while the other did not (CON). Wraps were removed at the 4-hour time point and measurements of skin temperature, blood flow, and intramuscular temperature were collected. Muscle biopsies were taken from the VL of each leg for later molecular analyses. Statistical significance (p < 0.05) was analyzed via paired t-tests. RESULTS: Skin temperature, measured via laser thermometer, was lower in COLD (34.84 ± 0.94 °C, to 13.15 ± 0.99 °C, p < 0.01). Similarly, thermal camera skin temperature measurements were (35.75 ± 0.94 °C, to 12.81 ± 0.93 °C, p < 0.01). Intramuscular temperature, via hypodermic thermocouple, also was lower in COLD (35.57 ± 0.76 °C, to 20.54 ± 1.31 °C, p < 0.01) after cold application. Blood flow, measured via ultrasound equipped with a transducer, did not change (0.64 ± 0.12 cm/sec, to 0.62 ± 0.17 cm/sec, p = 0.450). Arterial diameter was lower in COLD after 4 h (0.62 ± 0.05 mm, to 0.60 ± 0.05 mm, p = 0.018). Molecular outcomes (gene expression) will be measured soon via RT-qPCR and analyzed using the 2-∆∆ct method. CONCLUSIONS: Mitochondrial related gene expression data will help interpret previous local cold and exercise findings. Supported by NE-INBRE, NIGMS Funding (P20GM103427).