Changes in Cardiac Autonomic Regulation after Acute Lung Exposure to Carbon Nanotubes: Implications for Occupational Exposure

Carbon nanotubes (CNTs) are among the most relevant engineered nanomaterials (ENMs). Given the expected rise of exposure to ENMs, there is concern that they may adversely affect health of exposed people. Aim of the study was to test the hypothesis that single wall carbon nanotubes (SWCNTs) pulmonary exposure acutely affect the autonomic cardiovascular regulation in conscious rats. We studied Wistar-Kyoto rats in which a telemetry transmitter for continuous arterial pressure (AP) and heart rate (HR) recordings was surgically implanted. SWCNTs dispersed in phosphate buffer saline (PBS) or PBS alone were randomly administered intratracheally. Immediately before, and 24 hours after each instillation a 30 min AP recording was performed. The sequence analysis was performed to evaluate the baroreflex function. In the control group, PBS instillation did not induce any significant changes. At variance the SWCNT exposure induced a significant reduction of baroreflex system (BRS) ( 3 . 5 ± 0 . 6 versus 2 . 6 ± 0 . 4 0  msec/mmHg) without significant changes in the occurrence of baroreflex sequences ( 7 . 5 ± 0 . 4 7 % versus 7 . 4 ± 0 . 3 8 %). Our results show that SWCNT pulmonary exposure might affect the cardiovascular autonomic regulation thus contributing to cardiac and arrhythmic events.