Effect of cold exposure, exercise and high altitude on plasma endothelin-1 and endothelial cell markers in man.

The aims were to examine the effect of cold exposure, exercise and high altitude on plasma concentrations of big endothelin-1, endothelin-1, von Willebrand factor and serum e-selectin in twenty five healthy male volunteers. Clinical evaluation and venesection were performed before and after 24 hours of low altitude mountaineering, exposure to temperatures of -18 degrees C and +4 degrees C and whilst ascending from sea level to an altitude of 5000 m in the Karakoram. Plasma big endothelin-1, plasma endothelin-1 and serum soluble e-selectin concentrations were significantly elevated after two hours at -18 degrees C (p < 0.05, p < 0.05 and p < 0.01 respectively). At +4 degrees C, plasma big endothelin-1 and endothelin-1 concentrations rose significantly after 5 hours (p < 0.005 for both) but not after 2.5 hours. Low altitude mountaineering did not alter circulating marker concentrations. At high altitude, big endothelin-1 and endothelin-1 (p < 0.01 for both) rose significantly at 2500 m and initially at 5000 m but returned to sea level values after prolonged exposure to 5000 m. Serum e-selectin rose at all altitudes greater than sea level (p < 0.05). In conclusion, exposure to high altitude, moderate cold or freezing temperatures, but not exercise, selectively activates endothelial cells increasing endothelin-1 production. Cold exposure may contribute to the observed increase in plasma endothelin-1 in mountaineers at high altitude.