Altered Vascular Reactivity Following Exposure to Multi‐walled Carbon Nanotubes Increases Risk for Cardiac Injury

Abstract

The unique physicochemical properties of multi‐walled carbon nanotubes (MWCNT) present potential risks to physiological systems. We report here that an acute pulmonary instillation of MWCNT negatively impacts coronary flow (4.9 ± 0.6 ml/min/g vs. 6.8 ± 0.6 ml/min/g in vehicles) during reperfusion of isolated rat hearts subjected to global ischemia/reperfusion (I/R) injury. We hypothesized that MWCNT exposure blunts relaxation responses of vascular tissues. Male Sprague‐Dawley rats were exposed to 100 μg of MWCNT suspended in 10% surfactant/saline (10%SS) or the vehicle only. 24 hours later, segments of the left anterior descending (LAD) coronary and thoracic aorta were mounted on a multi‐myograph system. The segments were subjected to cumulative doses of acetylcholine (ACH), sodium nitroprusside (SNP), serotonin (5‐HT), or endothelin 1 (ET‐1). The LAD constrictor responses of the MWCNT group generated a greater magnitude of active stress (mN/mm2) to ET‐1 (4.03 ± 0.41 vs. 2.62 ± 0.23) and 5‐HT (3.76 ± 1.20 vs. 0.88 ± 0.34) compared to vehicle. Hillslope comparisons between groups revealed depressed aortic responses to ACH (−0.69 ± 0.23 vs. −1.95 ± 0.23) and ET‐1 (1.08 ± 0.09 vs. 1.74 ± 0.21) in the MWCNT group. From these data we conclude that an acute exposure to MWCNT can be deleterious to vascular reactivity and increases risks for cardiac injury. Supported by NIH ES019311 (JMB) & ES016246 (CJW).