Objective To evaluate the effect of long-term fine particulate matter (PM2.5) exposure on left ventricular morphology and function in C57BL/6 mice of different genders.
Methods Sixteen female and sixteen male C57BL/6 mice were randomly divided into PM2.5 filtered air (control) group and PM2.5 concentrated air (exposure) group, with eight mice in each group. PM2.5 exposure was performed using a Meteorological and Environmental Animal Exposure System, eight hours daily, six days a week, for 16 weeks. After exposure, the mice were anesthetized by isoflurane inhalation to measure morphological indicators such as left ventricular end-systolic and end-diastolic diameters, left ventricular end-systolic and end-diastolic volumes, left ventricular end-systolic and end-diastolic interventricular septum thickness, left ventricular end-systolic and end-diastolic posterior wall thickness, and left ventricle mass, as well as functional indicators such as ejection fraction, left ventricular short axis shortening, stroke volume, cardiac output, heart rate, and RR interval by highresolution small animal ultrasound imaging system.
Results The average concentration of PM2.5 in the exposure warehouse was (152.12±68.89) μg/m3, and that in the control warehouse was (9.45±0.99) μg/m3. Compared with the female mice in the control group (3.69±0.37) mm, (2.47±0.37) mm, (58.41±14.16) μL, (1.21±0.15) mm, (36.08±7.64) μL, (80.52±20.82) mg, and (21.05±7.41) μL, respectively, the left ventricular enddiastolic diameter (3.03±0.34) mm, left ventricular end-systolic diameter (1.82±0.21) mm, left ventricle end-diastolic volume (36.51±9.98) μL, left ventricular end-systolic septal thickness (0.93±0.23) mm, stroke volume (26.23±7.58) μL, left ventricle mass (54.85±15.35) mg, and cardiac output (13.47±4.16) mL/min were reduced in the female mice in the exposure group (P < 0.05); there was no significant change in the left ventricular morphology and the selected function indicators in the male mice after exposure to PM2.5. In the control group, except heart rate and left ventricular end-diastolic posterior wall thickness, there was no difference in the indices between female and male mice; in the exposure group, the female mice showed lower left ventricular endsystolic diameter, left ventricular end-diastolic diameter, left ventricular end-systolic volume, left ventricular end-diastolic volume, end-diastolic interventricular septal thickness, left ventricular mass, stroke volume, and cardiac output than the male mice (P < 0.05).
Conclusion PM2.5 exposure is a potential risk factor affecting left ventricular morphology and function. Long-term PM2.5 exposure has a great impact on left ventricular morphology in female mice.
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