Mechanism Research Of Heat Waves With Strong Sudden Cooling Weather’s Impact On Hypertension Diseases

Heat waves are the common catastrophic weather event in the summer of Nanjing. Heat waves can induce the cardiovascular and cerebrovascular discease and this were studied both at home and abroad. However, researchs concern the effects of heat waves with strong sudden cooling weather on cardiovascular and cerebrovascular disceases almost blank. Therefor, this article studied the mechanism of heat waves with strong sudden cooling on hypertension disease with spontaneously hypertensive rates experiment. This article also analyzed the characteristics of heat waves with strong sudden cooling weather and the effects on human mortality and morbidity in Nanjing. The main research conclusions of this article are as follows:(1) Hot days and heat waves appeared 914 days and 112 times respectively in Nanjing during 1951-2012 year. There were 13 times of heat waves and heat waves with strong sudden cooling weather apperred 6 times during 2005-2008 year,2010 and 2012 year.(2) The daily average deaths and onsets of hypertension disease in heat waves with strong sudden cooling weather were more than those in the whole summer of the same year. Middle-aged and elderly people were the high risk of hypertension disease groups. A certain range of cooling during the heat wave process could decrease the deaths and onsets of hypertension disease. However, with the decreasing of temperature enlarged, the deaths and onsets of hypertension disease increased rapiadlly.(3) As the stimulus of heat waves the levels of heat stress factors which included HIF-1α, HSP60, sICAM-1 increased obviously and thus led the white blood cells and platelet to aggregate and also caused inflammation in blood vessels. Meanwhile the activity of SOD decreased and the insufficient secretion of NO could affect the heat loss of body and lead the oxidation of lipoprotein to enhance and the level of blood lipid to increase, finally caused atherosclerosis. Moreover, the stimulus of sudden cooling during the heat wave process made the levels of cardiovascular risk factors which included TG, TC, LDL-C and Tn-T increase and the level of blood lipid increased further and the inflammation enhanced. Although the levels of stress factors decreased, they were still higher than the normal levels. Therefore these aggravate atherosclerosis and thrombosis further. The stress of sudden cooling also caused the sympathetic nervous system and renin angiotensin system to be activated and the level of vasoconstrictor factors to increase, made the cardiac cells to be excited, enhanced the power of cardiac muscle systole, raised the heart rate, increased the myocardial oxygen consumption, and finally caused the blood pressure raised significantly. The above may be the direct reason of the deaths and onsets of hypertension disease during the heat waves with strong sudden cooling process.