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EFFECTS OF INHALED COMBUSTION-DERIVED PARTICULATE MATTER ON INDICES OF CARDIAC, PULMONARY, AND THERMOREGULATORY FUNCTION IN SPONTANEOUSLY HYPERTENSIVE RATS
Citation:
Wichers, L. B., W. H. Rowan, J. P. Nolan, U P. Kodavanti, M. Schladweiler, A. D. Ledbetter, D L. Costa, AND W P. Watkinson. EFFECTS OF INHALED COMBUSTION-DERIVED PARTICULATE MATTER ON INDICES OF CARDIAC, PULMONARY, AND THERMOREGULATORY FUNCTION IN SPONTANEOUSLY HYPERTENSIVE RATS. Presented at Society of Toxicology, New Orleans, LA, March 6-10, 2005.
Description:
Epidemiological studies have shown a positive relationship between elevated levels of ambient particulate matter (PM) and rates of morbidity and mortality; these correlations are further strengthened when limited to individuals with preexisting cardiopulmonary diseases. While similar effects have been demonstrated in animals, the mechanism(s) by which these effects are mediated are unresolved. To further investigate this phenomenon, we examined the cardiac, pulmonary, and thermoregulatory effects of a combustion-derived PM (HP12), a particle with a more relevant metal profile (?Zn, ?V) and bioavailability than the residual oil fly ash used in many previous studies. Spontaneously Hypertensive (SH) rats were surgically implanted with radiotelemeters capable of continuously monitoring electrocardiogram (ECG), heart rate (HR), systemic arterial blood pressure (BP), and core temperature (Tco). Animals were divided into air and HP12 groups and exposed via inhalation (0 and 11 mg/m3, respectively) for 6hr/d?4d while inside whole-body plethysmograph chambers. This methodology permitted continuous, simultaneous monitoring and acquisition of cardiac and pulmonary physiological parameters in unanesthetized, unrestrained animals. Rats underwent blood collection and were sacrificed to obtain bronchoalveolar lavage (BAL) at 7 days post-exposure. We observed no changes in HR, BP, or Tco with exposure to inhaled HP12. However, ECG abnormalities, consisting of general rhythm disturbances and premature contractions, were observed in ?50% of HP12-exposed rats. There were slight increases in select blood and BAL indices, while there were only minor effects of HP12 on respiration parameters. Thus, this study demonstrated minimal deficits in cardiac function in SH rats after inhalation exposure to a low-metal content, "ambient-like", combustion-derived particle. (Abstract does not represent USEPA policy. This research was supported by EPA CT826513.)