Background Although paraoxonase 1 (PON1) is a high-density lipoprotein (HDL) associated antioxidant enzyme that has beneficial effects on atherosclerosis and cardiovascular disease, whether PON1 Q192R polymorphism have any effect on cardiac autonomic function is yet to be investigated. Moreover, there is limited data regarding the influence of NPs exposure on HRV parameters in humans. The purpose of the study was to exam whether PON1 genotype or NPs exposure has an association with HRV levels.

Methods This cross-sectional study recruited 235 workers exposed to NM and 185 non-exposed controls from 14 NM handling plants in Taiwan from 2009 to 2011. For each participant, we collected blood specimens to determine the genotype of the PON1 Q192R polymorphism and PON1 paraoxonase and arylesterase activities. In addition, short-term HRV was tested.

Results The results showed that PON1 Q192R genotype and PON1 paraoxonase/arylesterase activities associated with HRV, and was particularly noteworthy in RMSSD and HF. The relationship between NPs exposure and HRV was only found in workers exposed to nano-Ag, but the apparent relationship between NPs exposure and HRV is lacking.

Conclusions It is a novel finding that both RR genotype of PON1 (Q192R) and activities of PON1 increased with HRV levels. PON1 Q192R genotype may play an important role in cardiac protection. Considering the global prevalence of NMs market, further studies of NPs-induced cardiac events and stresses still are required to establish.