Interaction Effects of Ultrafine Carbon Black with Iron and Nickel on Heart Rate Variability in Spontaneously Hypertensive Rats

Abstract

BackgroundParticulate matter (PM) has been reported to be associated with alterations in heart rate variability (HRV); however, the results are inconsistent. We propose that different components of PM cause the discrepancy.ObjectiveIn this study, our goal was to determine whether different types of exposure would cause different HRV effects, and to verify the interactions between co-exposing components.MethodsUltrafine carbon black (ufCB; 14 nm; 415 μg and 830 μg), ferric sulfate [Fe2(SO4)3; 105 μg and 210 μg], nickel sulfate (NiSO4; 263 μg and 526 μg), and a combination of high-dose ufCB and low-dose Fe2(SO4)3 or NiSO4 were intratracheally instilled into spontaneously hypertensive rats. Radiotelemetry data were collected in rats for 72 hr at baseline and for 72 hr the following week to determine the response to exposure. Effects of exposure on 5-min average of normal-to-normal intervals (ANN), natural logarithm-transformed standard deviation of the normal-to-normal intervals (LnSDNN), and root mean square of successive differences of adjacent normal-to-normal intervals (LnRMSSD) were analyzed using self-control experimental designs.ResultsBoth high- and low-dose ufCB decreased ANN marginally around hour 30, with concurrent increases of LnSDNN. LnRMSSD returned to baseline levels after small initial increases. We observed minor effects after low-dose Fe and Ni instillation, whereas biphasic changes were noted after high-dose instillations. Combined exposures of ufCB and either Fe or Ni resulted in HRV trends different from values estimated from individual-component effects.ConclusionsComponents in PM may induce different cardioregulatory responses, and a single component may induce different responses during different phases. Concurrent exposure to ufCB and Fe or Ni might introduce interactions on cardioregulatory effects. Also, the effect of PM may be mediated through complex interaction between different components of PM.

Cardiopulmonary responses in spontaneously hypertensive and Wistar-Kyoto rats exposed to concentrated ambient particles from Detroit, Michigan

“…This is consistent with the bulk of the both the epidemiological (e.g., Devlin et al, 2003) and toxicological (e.g., Chen and Hwang, 2005) literature, which reports lower HRV parameters associated with PM exposure. Furthermore, the 2-3-ms difference in SDNN between CAPs-and air-exposed SH rats is similar to exposure-related changes in rodents from other PM studies that were found to be statistically significant (Pham et al, 2009;Chang et al, 2007). We suspect that with more animals per group (presently n = 4) that differences in HRV would also have been significant in this study.…”

Particulate Matter Air Pollution and Cardiovascular Disease

“…371 In general, reductions in several measures of HRV have been shown. [372][373][374][375][376] Most of the recent research has focused on exploring the roles of susceptibility and exposure characteristics. Decreases in heart rate and HRV indices have been reported to be pronounced in senescent mice, which indicates that aging may be a susceptibility factor.…”

Association of size-fractionated indoor particulate matter and black carbon with heart rate variability in healthy elderly women in Beijing

“…Black carbon (BC) from combustion sources is also considered an important indoor pollutant affecting people's health, and a World Health Organization report suggests that BC might be a particularly toxic component of PM . Animal experiments and epidemiological studies have demonstrated that BC levels are associated with changes in cardiac autonomic function by altering HRV indices . However, outdoor ambient PM is the focus of most research, and frequently, only a single‐size range of PM is considered.…”