OBJECTIVE: To investigate the mechanism and to explore the measures of prevention and treatment of hypothermal vasoconstriction. METHODS: By the techniques of endothelial cell culture and scanning electron microscopy, and vasomotor functional test of isolated vascular vessels, the relation of hypothermal vasoconstriction and the release of endothelium-derived contractile and vasodilative factors were observed. RESULTS: Hypothermia obviously induced vasoconstriction of isolated vascular vessels, whether endothelium was intact or removed, the lower the temperature, the higher the vascular tension. Removal of endothelium could decrease the effect of vasoconstriction by hypothermia. The conditioned medium of bovine aortic endothelial cell could induce significantly vasoconstriction of isolated rat common neck arterial ring in hypothermia. It indicated that the bovine aortic endothelial cells secreted contractile factors into the medium. Reheating to 37 degrees C or vasodilator or reheating plus vasodilator did not obviously influence the hypothermia-induced vasoconstriction within 2 hours. When reheating to 50 degrees C, vascular tension was decreased, but only changed in range of 28% to 42%. CONCLUSION: Hypothermia vasoconstriction is relative to vasoconstrictor factors secreted by endothelium. Reheating to 37 degrees C or vasodilator does not antagonize the constriction of vascular vessels. Reheating to 50 degrees C only partially eliminates the constrict effect of blood vessels, so the prevention of hypothermia vasoconstriction should be emphasized.