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CARDIOVASCULAR AND BLOOD COAGULATION EFFECTS OF PULMONARY ZINC EXPOSURE
Citation:
GILMOUR, P., A. NYSKA, M. SCHLADWEILER, J. K. MCGEE, G. WALLENBORN, J. E. RICHARDS, AND U. P. KODAVANTI. CARDIOVASCULAR AND BLOOD COAGULATION EFFECTS OF PULMONARY ZINC EXPOSURE. TOXICOLOGY AND APPLIED PHARMACOLOGY. Academic Press Incorporated, Orlando, FL, 211(1):41-52, (2006).
Impact/Purpose:
To demonstrate cardiac, coagulative, and fibrinolytic alterations using a rat model of pulmonary exposure to zinc
Description:
Cardiovascular damage induced by pulmonary exposure to environmental chemicals can result from direct action or, secondarily, from pulmonary injury. We have developed a rat model of pulmonary exposure to zinc to demonstrate cardiac, coagulative, and fibrinolytic alterations. Male Wistar Kyoto rats were instilled intratracheally with saline or zinc sulfate (2 umol/kg); the alterations were determined at 1, 4, 24, and 48 h postexposure. High-dose zinc enabled us to show changes in circulating levels of zinc above normal and induce significant pulmonary inflammation/injury such that cardiac impairments were likely. At 124 h postexposure, plasma levels of zinc increased at to nearly 20% above the base line. Significant pulmonary inflammation and injury were determined by analysis of bronchoalveolar lavage fluid and histopathology in zinc-exposed rats at all time points. Starting at 4 h postexposure, pulmonary damage was accompanied by persistently increased gene expressions of tissue factor (TF) and plasminogen activator-inhibitor-1 (PAI-1), but not thrombomodulin (TM). Cardiac tissues demonstrated similar temporal increases in expressions of TF, PAI-1, and TM mRNA following pulmonary instillation of zinc. In contrast to extensive pulmonary edema and inflammation, only modest, but focal and acute, myocardial lesions developed in a few zinc-exposed rats; no histological evidence showed increased deposition of fibrin or disappearance of troponin. At 24 and 48 h postexposure to zinc, increases occurred in levels of systemic fibrinogen and Factor X, and the activated partial thromboplastin times became elevated. These data suggest that zinc-induced, cardiac blood coagulative changes occur following acute pulmonary inflammation and injury, possibly resulting from a direct effect of zinc on the heart or secondary to pulmonary damage or both. Cardiovascular impairments following acute respiratory injury may play an important role in adverse health outcomes following environmental exposures.