Effects of chronic secondhand smoke exposure on cardiovascular regulation and the role of soluble epoxide hydrolase in mice

Shiyue Pan; Emma Karey; Madeline Nieves-Cintron; Yi-Je Chen; Sung Hee Hwang; Bruce D Hammock; Kent E Pinkerton; Chao-Yin Chen

doi:10.3389/fphys.2023.1185744

Effects of chronic secondhand smoke exposure on cardiovascular regulation and the role of soluble epoxide hydrolase in mice

Front Physiol. 2023 Jun 8:14:1185744. doi: 10.3389/fphys.2023.1185744. eCollection 2023.

Authors

Shiyue Pan¹, Emma Karey¹, Madeline Nieves-Cintron¹, Yi-Je Chen¹, Sung Hee Hwang², Bruce D Hammock², Kent E Pinkerton³, Chao-Yin Chen¹

Affiliations

¹ Department of Pharmacology, University of California Davis, Davis, CA, United States.
² Department of Entomology and Nematology, UC Davis Comprehensive Cancer Center, University of California Davis, Davis, CA, United States.
³ Center for Health and the Environment, University of California Davis, Davis, CA, United States.

Abstract

Background: Secondhand smoke (SHS) is a significant risk factor for cardiovascular morbidity and mortality with an estimated 80% of SHS-related deaths attributed to cardiovascular causes. Public health measures and smoking bans have been successful both in reducing SHS exposure and improving cardiovascular outcomes in non-smokers. Soluble epoxide hydrolase (sEH) inhibitors have been shown to attenuate tobacco exposure-induced lung inflammatory responses, making them a promising target for mitigating SHS exposure-induced cardiovascular outcomes. Objectives: The objectives of this study were to determine 1) effects of environmentally relevant SHS exposure on cardiac autonomic function and blood pressure (BP) regulation and 2) whether prophylactic administration of an sEH inhibitor (TPPU) can reduce the adverse cardiovascular effects of SHS exposure. Methods: Male C57BL/6J mice (11 weeks old) implanted with BP/electrocardiogram (ECG) telemetry devices were exposed to filtered air or 3 mg/m³ of SHS (6 hr/d, 5 d/wk) for 12 weeks, followed by 4 weeks of recovery in filtered air. Some mice received TPPU in drinking water (15 mg/L) throughout SHS exposure. BP, heart rate (HR), HR variability (HRV), baroreflex sensitivity (BRS), and BP variability were determined monthly. Results: SHS exposure significantly decreased 1) short-term HRV by ∼20% (p < 0.05) within 4 weeks; 2) overall HRV with maximum effect at 12 weeks (-15%, p < 0.05); 3) pulse pressure (-8%, p < 0.05) as early as week 4; and 4) BRS with maximum effect at 12 weeks (-11%, p < 0.05). Four weeks of recovery following 12 weeks of SHS ameliorated all SHS-induced cardiovascular detriments. Importantly, mice exposed to TPPU in drinking water during SHS-related exposure were protected from SHS cardiovascular consequences. Discussion: The data suggest that 1) environmental relevant SHS exposure significantly alters cardiac autonomic function and BP regulation; 2) cardiovascular consequences from SHS can be reversed by discontinuing SHS exposure; and 3) inhibiting sEH can prevent SHS-induced cardiovascular consequences.

Keywords: autonomic function; baroreflex sensitivity; cardiovascular effect; heart rate variability; sidestream smoke; soluble epoxide hydrolase.

Abstract

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