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HYPERTENSIVE AND TACHYCARDIC RESPONSES TO ORAL TOLUENE IN THE RAT.
Citation:
GORDON, C. J., W. M. OSHIRO, T. E. SAMSAM, P. BECKER, C. M. MACK, AND P. J. BUSHNELL. HYPERTENSIVE AND TACHYCARDIC RESPONSES TO ORAL TOLUENE IN THE RAT. . Presented at International Neurotoxicology Conference, Research Triangle Park, NC, NC, September 11 - 14, 2005.
Description:
Little is known regarding the effects of toluene and other volatile organic compounds on autonomic processes. Such studies should be performed in unrestrained and undisturbed animals to avoid the effects of handling stress on processes regulated by the autonomic nervous system. This study determined the effects of oral toluene on blood pressure (BP), heart rate (HR), core temperature (Tc), and motor activity (MA) in unrestrained rats. Male, Long-Evans rats were surgically implanted with radiotransmitters (Data Sciences, St. Paul, MN) to monitor BP, HR, Tc, and MA. Telemetry data were recorded continuously in undisturbed rats housed individually at an ambient temperature of 22 �C while allowed to drink and feed ad libitum. Toluene in a corn oil vehicle was administered by gavage at doses of 0, 0.4, 0.8, and 1.2 g/kg at 11:30 hr while the telemetry data were monitored over 48 hours. Dosing with corn oil led to transient elevations in BP, HR, Tc, and MA that were attributed to the stress of handling. All doses of toluene led to transient increases in BP and HR that exceeded the control response during the first 30-60 min after dosing. Toluene elicited elevations in BP and HR that persisted for several hours after dosing. BP was elevated by 20 mmHg over controls at 4 hr after dosing with 1.2 g/kg toluene. HR remained elevated above controls by approximately 25 and 50 b/min in the 0.8 and 1.2 g/kg groups, respectively. Tc increased above controls for several hours after treatment with 1.2 g/kg. MA increased above control levels during the first hr after dosing. There was gradual recovery followed with a secondary rise in MA in rats dosed with 1.2 g/kg. Overall, toluene at oral doses of 0.4 to 1.2 g/kg affected the autonomic control of blood pressure and body temperature. The effects of oral dosing are likely to be comparable to that of inhalation exposures. The highest toluene dose of 1.2 g/kg induced a marked tachycardia, hypertension, hyperactivity, and mild hyperthermia. These autonomic responses are important for the development of PBPK models for toluene and other volatile organic compounds. This is an abstract of a proposed presentation and does not necessarily reflect EPA policy.