Monday, January 19, 2009

Zinc Salt Instillation causes Cardiovascular Effects

Toxicology and Applied PharmacologyVolume 211, Issue 1, 15 February 2006, Pages 41-52
Cardiovascular and blood coagulative effects of pulmonary zinc exposure
Peter S. Gilmoura, Abraham Nyskab, Mette C. Schladweilerc, John K. McGeec, J. Grace Wallenbornd, Judy H. Richardsc and Urmila P. Kodavantic, ,
aCenter for Environmental Medicine, Asthma and Lung Biology, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
bLaboratory of Experimental Pathology, National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709, USA
cPulmonary Toxicology Branch, MD B143-01, Experimental Toxicology Division, National Health and Environmental Effects Research Laboratory, ORD, US Environmental Protection Agency, Research Triangle Park, NC 27711, USA
dDepartment of Environmental Sciences and Engineering, UNC School of Public Health, Chapel Hill, NC 27599, USA
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, 131 μg/kg (2 μmol/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 1–24 h postexposure, plasma levels of zinc increased 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 mild, and focal 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 the activated partial thromboplastin time. These data suggest that cardiovascular blood coagulation impairments are likely following pulmonary zinc exposure and associated pulmonary injury and inflammation.

BrooklynDodger(s) comment: This does appears to be a soluble zinc source. In occupational health practice, zinc and other metals are most associated with metal fume fever, which is usually discounted as a transient condition. Exposure response data on MFF are lacking in people, although the Dodger(s) believe MFF occurs at exposures less than the 5 mg/m3 PEL. An animal model for MFF would then enable titrating respiratory against the circulatory endpoints here. The doses in this study did not result in really large increases in circulating zinc levels.

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