Background: The reaction of vascular endothelial cells to occlusion and heat in Southeast Asian Indians (SAI) compared to Caucasians (C) has not been studied, although genetic differences are found in endothelial cells between the races.
Material/Methods: Ten C and Ten SAI (<35 years old) male and female subjects participated. There was no difference in the demographics of the subjects except that the SAI group had been in the United States for 6 months; C was natives to the US. Endothelial function was assessed by the response of the circulation (BF) to local heating and the response to vascular occlusion. The effects of local heat on circulation in the skin on the forearm was assessed by applying heat for 6 minutes at temperatures, 38, 40 and 42°C on 3 separate days. On different days, vascular occlusion was applied for 4 minutes to the same arm and skin blood flow was measured for 2 minutes after occlusion; skin temperature was either 31°C or 42°C.
Results: When occlusion was applied at a skin temperature of 31°C, the BF response to occlusion was significantly lower in the SAI cohort compared to C (peak BF C=617±88.2 flux, SAE=284±73 flux). The same effect was seen at skin temperatures of 42°C. The circulatory response to heat was also significantly less in SAI compared to C at each temperature examined (p<0.05)(for temperatures of 38, 40 and 42°C, peak blood flow for C was 374.7±81.2, 551.9±91.3 and 725.9±107 flux respectively and 248.5±86.2, 361.4±104.3 and 455.3±109.7 flux respectively for SAI. (p<0.05).
Conclusions: Thus there seems to be big differences in these 2 populations in endothelial response to these stressors. The difference may be due to genetic variations between the 2 groups of subjects.

Keywords: Laser-Doppler Flowmetry, India - ethnology, European Continental Ancestry Group, Endothelial Cells - physiology, California, Body Composition - physiology, Regional Blood Flow - physiology, Skin - blood supply, Skin Temperature