模拟热浪期间突然强降温天气对高血压大鼠心血管系统影响的实验研究

Effects of Simulated Heat Waves with Strong Sudden Cooling Weather on the Cardiovascular System of Spontaneously Hypertensive Rats

通过模拟热浪期间突然强降温天气对高血压大鼠影响的实验研究,探讨热浪期间突然强降温对高血压大鼠心血管疾病的影响机理。应用TME1880气象环境模拟箱模拟了南京2006年6月19日5时至22日11时高温热浪期间突然强降温天气过程,将24只高血压大鼠随机分为实验组(包括热浪组、降温组和复温组)和对照组,每组各6只大鼠。把实验组放入模拟箱内,使其受热浪期间突然强降温天气过程影响,分别在模拟热浪期间突然强降温天气过程55、59和75 h时,先后取出热浪组、降温组和复温组监测基本生理指标;并采用断头采血和摘取心尖,测量各组高血压大鼠的热应激因子(HSP60、SOD、s ICSM-1、HIF-1α)、冷应激因子(NE、EPI、ANGⅡ)、血管收缩因子(ET-1、NO)以及心血管的危险因素(TC、TG、HDL-C、LDL-C和Tn-T)生化指标的含量。结果表明受高温热浪的影响,高血压大鼠的热应激因子除SOD含量明显下降以外其他热应激因子含量均明显增加,冷应激因子均明显下降,血管收缩因子ET-1下降而NO上升,心脑血管危险因素除TG上升以外其余因子均有不同程度的下降。热浪期间突然强降温可导致高血压大鼠热应激因子除SOD上升以外其余均下降,冷应激因子全部上升,血管收缩因子ET-1上升而NO下降,心血管危险因素均上升。通过分析可知,热浪可使得高血压大鼠动脉粥样硬化加剧,热浪期间突然强降温使得NE和ANGⅡ含量明显增加,加剧血压升高。受降温的影响Tn-T明显增多,说明突然的强降温冷刺激导致的血管收缩导致了心肌缺血,加上血脂四项的升高使得高血压大鼠心血管疾病进一步加重。初步探讨了热浪期间突然强降温天气对高血压大鼠心血管疾病的影响。

Spontaneously hypertensive rats were used to determine the effects of heat waves with strong sudden cooling exposure in a climate chamber. We used a TEM1880 meteorological-environment chamber to simulate heat waves with strong sudden cooling weather in accordance with the data obtained at 5 a. m. of 19 June 2006 to 11 p. m. of 22 June 2006 in Nanjing. Twenty-four spontaneously hypertensive rats were randomly divided into experimental groups（ heat wave group,temperature drop group,and rewarming temperature group） and control group.The experimental groups were placed in the climate simulator chamber for exposure to the simulated heat wave with strong sudden temperature drop. After 55,59,and 75 h of exposure,the heat wave,temperature drop,and rewarming temperature groups were successively removed from the chamber for monitoring of physiological indicators.Blood samples were collected by decollation,and the apex of the rat hearts were harvested in all groups. The levels of heat stress factors（ HSP60,SOD,s ICSM-1,and HIF-1α）,cold stress factors（ NE,EPI,and ANG II）,vasoconstrictor factors（ ET-1 and NO）,and cardiovascular risk factors（ TC,TG,HDL-C,LDL-C,and Tn-T） were measured in each spontaneously hypertensive rat. Results showed that heat wave increased the levels of heat stress factors,except for the decreased level of SOD,and decreased the levels of cold stress factors,vasoconstrictor factors and cardiovascular risk factors,except for the increased levels of NO and TG. The strong sudden temperature drop in the heat wave process decreased the levels of heat stress factors,except for the increased levels of SOD,and increased the levels of cold stress and vasoconstrictor factors and cardiovascular and cerebrovascular risk factors,except for the decreased level of NO. Analysis showed that heat waves could enhance the atherosclerosis of spontaneously hypertensive rats,and strong sudden cooling could increase the plasma concentrations of NE and ANGII,resulting in increased blood pressure. Strong cooling evidently increased Tn-T levels. Hence,strong sudden cooling could cause vasoconstriction and lead to myocardial ischemia. Furthermore,increased blood lipid levels aggravated cardiovascular diseases in the spontaneously hypertensive rats. This study revealed the mechanism underlying the influence of heat waves with sudden cooling on cardiovascular diseases in spontaneously hypertensive rats.