Effects of Simulated Heat Wave on Senile Mice

Effects of simulated heat wave on senile mice were investigated in the present study. Heat wave was simulated in a meteorological environment simulation chamber according to a heat wave occurred in July 2001 in Nanjing, China. Eighteen senile mice were divided into control group, heat wave group, and heat wave BH4 group. Mice in heat wave and BH4 groups were exposed to simulated heat waves in the simulation chamber. Mice in BH4 group were treated with gastric lavage with BH4 2h prior to heat wave exposure. Weight and rectal temperature were recorded daily. Levels of soluble intercellular adhesion molecule (sICAM-1), endothefin (ET-1) and nitric oxide (NO) in plasma were determined at the end of the experiment as biomarkers of cardiac function. Heat wave significantly raised body temperature. However, mice in heat wave group had significantly higher NO level and sICAM-1and lower ET-1 compared with mice in control group (P < 0.01); indicating that heat wave had negative effect on cardiac function in senile mice. When the heat wave duration is longer, heat stress response of senile mice will be more intense, heat stroke and other cardiovascular diseases may occur. Rectal temperature and sICAM-1 content in BH4 group had no significant difference with that in control group (P>0.05) while NO increased apparently (P<0.01). Collectively, these beneficial effects demonstrate that BH4 may potentially mitigate the risk of coronary heart disease in human under heat wave exposure.