Effects of different cold-air exposure intensities on the risk of cardiovascular disease in healthy and hypertensive rats

Abstract

Ten-week-old male Wistar rats (systolic blood pressure, 106-116 mmHg; body weight, 300-320 g) and spontaneously hypertensive rats (systolic blood pressure, 160-176 mmHg; body weight, 210.9-244.9 g) were used as healthy and hypertensive subjects to determine the effects of varying degrees of cold-air exposure in a climate chamber box. The three cold-air ranks were cold air I [minimum temperature (TMIN) 6.4 °C, ↓∆T48 8.6 °C], cold air II (TMIN 3.8 °C, ↓∆T48 11.2 °C), and cold air III (TMIN -0.3 °C, ↓∆T48 15.3 °C), as established from the cold-air data of Zhangye City, China. Each cold-air rank consisted of a temperature drop and a temperature increase with the same initial and terminal temperatures (15 °C). After cold-air exposure, the risk factors for cardiovascular disease (CVD) such as systolic blood pressure, whole blood viscosity (10/s and 150/s), plasma fibrinogen, and blood lipids of the rats were determined. The results indicated that the CVD risk factors of the healthy and hypertensive rats increased significantly with cold-air exposure intensities. The increase in systolic blood pressure was greater during temperature drops, whereas the increases in whole blood viscosity and plasma fibrinogen were greater after cold-air exposure. The effects of cold-air exposure on the CVD risk factors of healthy rats, particularly the systolic blood pressure, whole blood viscosity (150/s), and LDL/HDL, were greater than those in hypertensive rats. In conclusion, CVD risk may increase with cold-air ranks. Blood pressure-induced CVD risk may be greater during cold-air temperature drop, whereas atherosclerosis-induced CVD risk may be greater after cold-air exposure. The effect of cold air on the CVD risk factors in healthy subjects may be more significant than those in hypertensive subjects.

Health assessment of future PM2.5 exposures from indoor, outdoor, and secondhand tobacco smoke concentrations under alternative policy pathways in Ulaanbaatar, Mongolia

“…Attributable burden estimates in UB may, in general, be underestimated. Evidence suggests that cold-air exposures may increase sensitivity to risk factors for cardiovascular diseases [ 51 ]. Ulaanbaatar’s temperatures are typically much colder than the regions that inform Burnett et al’s exposure-response models [ 33 ], suggesting a risk misclassification biasing our burden estimates downward.…”

Effects of Simulated Heat Waves with Strong Sudden Cooling Weather on ApoE Knockout Mice

“…These experiment results suggest that a continuous heat wave minimally affects EPI but decreases NE levels. The strong sudden temperature drop during the heat wave process can increase NE and EPI levels, resulting in excitation of the sympathetic nervous system, inducing vasomotor effects and increased blood pressure [ 14 , 15 , 16 , 17 , 18 ], leading to CVD exacerbation [ 17 ].…”

“…The strong sudden temperature drop during the heat wave process evidently affected the ANG II levels of ApoE−/− mice, and a continuous heat wave could decrease ANGII, causing blood vessels to expand [ 4 ], and be conducive to losing heat. Strong sudden temperature drops can significantly increase ANGII, induce vasomotor effects, and cause high blood pressure [ 14 , 15 , 16 , 17 , 18 ], leading to CVD exacerbation [ 17 ]. The strong sudden temperature drop during the heat wave process could affect the blood lipid levels of ApoE−/− mice.…”

Effects of Cold Air on Cardiovascular Disease Risk Factors in Humans

“…The Lanzhou Central Meteorological Observatory provided cold air weather data, including temperature, atmospheric pressure, weather forecast for cold air activity, and other hourly monitoring data. Cold air weather event was determined according to China's Cold Air Level National Standard GB/T20484-2006 developed by the Central Meteorological Observatory in 2006 [13]. Statistical Methods: SPSS13.0 software was used for statistical data analysis.…”

“…Previous research [6] suggested that weather in winter half year or summer half year, in Changchun City, both the sharp changes in air pressure and temperature are prone to cause coronary heart disease relapse, the relatively huge rise of air pressure and fall of air temperature are unfavorable to cerebral hemorrhage and cerebral infarction, and the high blood pressure is mainly related to air pressure fluctuations and relatively humid weather. Acute cold stimulation can increase systolic blood pressure above 20 mmHg in humans [7][8][9], and the transient low temperature stimulation can rapidly increase blood pressure both in humans and animals [10][11][12][13][14]. Several epidemio-logical studies demonstrated that low temperature during the cold season can result in hypertensive diseases [15] and rise the frequency of hypertension-associated cardiovascular diseases, for example, myocardial infarction and stroke [16][17][18].…”