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Published on: July 21, 2023
The Acute Effects of Age and Particulate Matter Exposure on Heart Rate and Heart Rate Variability in Mice
Blake A Bennett1,2, Ernst W Spannhake3, Ana M Rule3
1Oregon Health & Science University-Portland State University School of Public Health, 506 SW Mill St., Suite 450, Portland, OR, 97201, USA. bben2@pdx.edu.
Abstract:
Exposure to ambient particulate matter (PM) is associated with increased cardiac morbidity and mortality with the elderly considered to be the most susceptible. The purpose of this study was to determine if exposure to PM would cause a greater impact on heart regulation in older DBA/2 (D2) male mice as determined by changes in heart rate (HR) and heart rate variability (HRV). D2 mice at the ages of 4, 12, and 19 months were instilled with 100 µg of PM or saline by aspiration. Before and after the aspiration, 3-min echocardiogram (ECG) samples for HR and HRV were recorded at 15-min intervals for 3 h along with corresponding measurements of homeostasis, such as temperature, metabolism, and ventilation. PM exposure resulted in an increase in HRV, declines in HR, and altered measures of homeostasis for a subset of the 12-mo mice. The PM aspiration did not affect cardiac or homeostasis parameters in the 4- or 19-mo mice. Our results suggest that a select group of middle-age mice are more susceptible to alterations in their heart rhythm after PM exposure and highlight that there are acute age-related differences in heart rhythm following PM exposure.
Insights
Particulate matter (PM) exposure impacts heart regulation, especially in middle-aged mice. This study found middle-aged mice showed altered heart rate variability and homeostasis after PM exposure, unlike younger or older mice.
Area of Science:
- Environmental Health
- Cardiovascular Physiology
- Gerontology
Background:
- Ambient particulate matter (PM) exposure is linked to cardiovascular disease, with the elderly being most vulnerable.
- Understanding age-specific responses to PM is crucial for public health.
- DBA/2 (D2) mice provide a model for studying age-related cardiac function.
Purpose of the Study:
- To investigate the impact of particulate matter (PM) exposure on heart rate (HR) and heart rate variability (HRV) in aging DBA/2 (D2) male mice.
- To determine age-related susceptibility to PM-induced cardiac and homeostatic changes.
- To assess acute effects of PM on cardiac regulation and homeostasis across different ages.
Main Methods:
- D2 mice (4, 12, and 19 months old) received 100 µg of PM or saline via aspiration.
- Echocardiogram (ECG) recordings for HR and HRV were taken before and after aspiration over 3 hours.
- Homeostasis parameters including temperature, metabolism, and ventilation were monitored concurrently.
Main Results:
- Particulate matter (PM) exposure led to increased heart rate variability (HRV), decreased heart rate (HR), and altered homeostasis in a subset of 12-month-old mice.
- No significant effects on cardiac or homeostasis parameters were observed in 4-month-old or 19-month-old mice.
- These findings indicate acute age-dependent cardiac responses to PM exposure.
Conclusions:
- Middle-aged DBA/2 mice exhibit heightened susceptibility to cardiac rhythm alterations following particulate matter (PM) exposure.
- Acute exposure to PM can differentially affect heart rhythm and homeostasis based on age.
- The study highlights the importance of considering age in assessing the cardiovascular risks of air pollution.
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