A single exposure to extreme heat alters cardiovascular function in normotensive and spontaneously hypertensive rats.
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Climate change has resulted in both extreme heat events and an overall increase in average ambient temperatures and severe weather. Extreme heat conditions combined with other psychosocial and physiological factors may decrease health resiliency and trigger sudden adverse responses. With continual increases in extreme heat events, both healthy individuals and those with underlying disease may be susceptible to increases in morbidity and mortality. This study was designed to examine the effects of a single extreme heat exposure on the cardiovascular response of 9–10-week-old Wistar-Kyoto (WKY) normotensive and spontaneously hypertensive (SH) rats. Rats were exposed to either normal temperature (70 °F) or extreme heat (100 °F) for 30 minutes and underwent left intraventricular function assessments 24hrs later. SH rats had higher heart rate (HR), blood pressure (BP), and left ventricular volume (LVV), and lower left ventricular pressure (LVP) than WKYs. Extreme heat caused LVV to increase and LVP and HR to decrease significantly in SH rats. WKY rats exposed to extreme heat only had significantly lower LVV when compared to normal temperature. SH rats also had a trend of decreased BP due to extreme heat. These results indicate that a single extreme heat event can alter cardiovascular function in both normotensive and hypertensive rats. Moreover, the results suggest that underlying cardiovascular disease can increase sensitivity to extreme heat exposure.
(This abstract does not reflect EPA policy).