Effect of higenamine on the proliferation of cold-treated HDMECs and NO production in vivo. (A) The proliferation rate of hypothermia HDMEC stimulated by higenamine were detected by MTT assay. *P<0.05, **P<0.01 vs. the control group. (B) NO concentration in the supernatant of HDMECs. Statistical analysis was performed using the one-way analysis of variance followed by Dunnett's test analysis. **P<0.01 vs. the NT group. ##P<0.01 vs. the HB group. HH, hypothermia+higenamine; HP, hypothermia+Positive control drug; HB, hypothermia; NT, Normal temperature; NO, nitric oxide; HDMECs, human dermal microvascular endothelial cells.