Electroencephalographic and autonomic responses to trichloroethylene inhalation in freely moving rats
- 24 Downloads
Effects of trichloroethylene (TRI) on the central nervous system (CNS) and autonomic functions were examined by means of continuous polygraphic measurements of electroencephalogram (EEG), electromyogram (EMG) and electrocardiogram (ECG) in electrode-implanted and freely moving rats, while they were exposed via inhalation to TRI vapor of 300, 1000 or 3000 ppm for 8 h/day or 6000 ppm for 4 h/day on 3 consecutive days. The exposures to 3000 and 6000 ppm produced abnormal EEG activity and incapacitation of postural maintenance during the exposure period, while the post-exposure period was characterized by decreased waking (W) time, lowered heart rate (HR) and increased numbers of bradyarrhythmic episodes after recovery from anesthesia. The exposure to 1000 ppm decreased W time without the appearance of anesthesia. The exposure to 300 ppm did not produce any observable effects except the lowered HR, which occurred during the post-exposure period. The relationships between internal doses of TRI and its metabolites and these TRI-induced pathophysiological responses were determined by blood and brain analyses of TRI, trichloroethanol and trichloroacetic acid in the TRI-exposed rats. Recordings of respiratory chest wall movement revealed that the number of TRI-induced bradyarrhythmias accompanying apnea during paradoxical sleep (PS) increased significantly after cessation of exposure to 6000 ppm TRI. This suggests that TRI-induced hypoxemia due to apnea during PS triggers bradyarrhythmogenesis through increased cardiac vagal efferent tone.
Key wordsTrichloroethylene Sleep-wakefulness Heart rate Bradyarrhythmia Sleep apnea
Unable to display preview. Download preview PDF.
- Bardodej JZ, Vyskocil J (1955) The problem of trichloroethylene in occupational medicine. AMA Arch Indust Health 13: 581–592Google Scholar
- James WRL (1963) Fatal addiction to trichloroethylene. J Indust Med 20: 47–49Google Scholar
- Kawakami T, Takano T, Araki R (1988) Synergistic interaction of triand tetra-chloroethylene, hypoxia, and ethanol on the atrioventricular conduction of the perfused rat heart. Indust Health 26: 25–33Google Scholar
- Kleinfeld M, Tabershaw IR (1954) Trichloroethylene toxicity. Arch Ind Hyg Occup Med 10: 134–141Google Scholar
- Mikiskova H, Mikiska A (1966) Trichloroethanol in trichloroethylene poisoning. Br J Indust Med 23: 116–125Google Scholar
- Nakajima T, Okino T, Kurasawa K, Murayama N, Sato A (1987) Chemical burns, bradycardia, extrasystolic arrhythmia, and unconsciousness caused by accidental trichloroethylene exposure (in Japanese). Jpn J Ind Health 29: 72–73Google Scholar
- Nakamura K (1985) Mortality patterns among cleaning workers. Jpn J Ind Health 27: 24–37Google Scholar
- Nomiyama K (1978) Three clinical cases of trichloroethylene-exposed workers with the central nervous system impairment (in Japanese). Jpn J Ind Health 20: 526Google Scholar
- Seppäläinen AM, Antti-Poika M (1983) Time course of electrophysiological findings for patients with solvent poisoning. Scand J Work Environ Health 9: 15–24Google Scholar
- Winer BJ (1971) Statistical principles in experimental design, 2nd edn. McGraw-Hill, New YorkGoogle Scholar