Abstract
The potential uses of engineered C₆&sub0; fullerene (C₆&sub0;) have expanded in recent decades to include industrial and biomedical applications. Based on clinical findings associated with particulate matter exposure and our data with multi-walled carbon nanotubes, we hypothesized that ischemia/reperfusion (I/R) injury and pharmacological responses in isolated coronary arteries would depend upon the route of exposure and gender in rats instilled with C₆&sub0;. Male and female Sprague Dawley rats were used to test this hypothesis by surgical induction of cardiac I/R injury in situ 24 h after intratracheal (IT) or intravenous (IV) instillation of 28 μg of C₆&sub0; formulated in polyvinylpyrrolidone (PVP) or PVP vehicle. Serum was collected for quantification of various cytokines. Coronary artery segments were isolated for assessment of vasoactive pharmacology via wire myography. Both IV and IT exposure to C₆&sub0; resulted in expansion of myocardial infarction in male and female rats following I/R injury. Serum-collected post-I/R showed elevated concentrations of interleukin-6 and monocyte chemotactic protein-1 in male rats exposed to IV C₆&sub0;. Coronary arteries isolated from male rats exposed to IT C₆&sub0; demonstrated augmented vasocontraction in response to endothelin-1 that was attenuated with Indomethacin. IV C₆&sub0; exposure resulted in impaired acetylcholine relaxation in male rats and IT C₆&sub0; exposure resulted in depressed vasorelaxation in response to sodium nitroprusside in female rats. Based on these data, we conclude that IT and IV exposure to C₆&sub0; results in unique cardiovascular consequences that may favor heightened coronary resistance and myocardial susceptibility to I/R injury.