The impact of increased living temperature on the cardiopulmonary response of male and female mice to benzene toluene ethylbenzene and xylene (BTEX).

Abstract

Objective: Benzene, toluene, ethylbenzene, and xylene (BTEX) are ubiquitous pollutants, and leakage of underground storage tanks has increased the risk of inhalation exposure and health effects that are likely impacted by ambient temperature.

Methods: In this study, male and female C57BL6J mice were housed at either normal (NT - 70 °F/22 °C) or high temperature (HT - 90 °F/32 °C) for five weeks, followed by nose-only exposure to either filtered air (FA) or BTEX (316 ppm) for four hours on two consecutive days. Whole-body plethysmography was performed after the first exposure and high-frequency echocardiography after the second.

Results: HT significantly increased tidal volume (TV), and inspiratory/expiratory times (Ti/Te) and flows (PIF/PEF) and decreased enhanced pause (Penh) in female and male mice. At NT, BTEX increased frequency (f) and decreased Ti and Te in female mice but not male. At HT, BTEX decreased f and Penh and increased TV, Te, Ti, and relaxation time (RT) in female mice, and only increased TV, PEF, PIF in males. HT caused a significant decrease in heart rate in female mice, while BTEX reversed that effect. Dobutamine increased HR in all HT females and cardiac output (CO) in males. BTEX decreased HR and CO in the latter.

Discussion: Thus, BTEX altered breathing and cardiovascular function in a sex-dependent manner, causing rapid ventilation in females, irrespective of temperature, whereas BTEX caused cardiovascular decrements in only HT males challenged with exercise-like stress. These results indicate that sex and ambient temperature play a role in BTEX cardiopulmonary effects, which underscores their importance for air pollution risk.