Effects of cold-water immersion on VEGF mRNA and protein expression in heart and skeletal muscles of rats

Aim: The effects of cold exposure on gene and protein expression of vascular endothelial growth factor (VEGF), in heart and skeletal muscles, were studied in male adult Wistar rats. Methods: Cold immersion was accomplished by submerging the rats in shoulder-deep water maintained at ∼18 °C, either acutely (1 h) or chronically (1 h day^-1, 5 days week^-1 for 20 weeks). The expressions of VEGF mRNA and protein in heart, gastrocnemius, and soleus muscles were examined by Northern and Western blotting and competitive-polymerase chain reaction techniques. Results: The expressions of VEGF mRNA and protein were markedly increased in cardiac muscle of the cold-immersed group, particularly in the 1-hour exposure group, whereas VEGF mRNA and protein in gastrocnemius were decreased significantly after an acute exposure. Although the protein level in gastrocnemius remained low in the chronically exposed group, the expression of mRNA of VEGF₁₆₅ with chronic exposure in this group returned to the control level and that of VEGF₂₀₆ was 15% greater than that in controls. The expression of mRNA for VEGF₁₆₅ in soleus was also lowered by acute cold exposure, although that for VEGF₂₀₆ was stable. However, VEGF protein was increased by 50%. After 20 weeks, all of these parameters were increased over the levels found in the controls. Conclusion: These results suggest that the VEGF gene may be a major regulatory factor in cardiac and skeletal muscle adaptation to the cold environment stimulating angiogenesis and thermogenesis.