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Autonomic nervous system dysfunction in workers exposed to lead, zinc, and copper in relation to peripheral nerve conduction: A study of R‐R interval variability
Author(s) -
Murata Katsuyuki,
Araki Shunichi
Publication year - 1991
Publication title -
american journal of industrial medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.7
H-Index - 104
eISSN - 1097-0274
pISSN - 0271-3586
DOI - 10.1002/ajim.4700200509
Subject(s) - medicine , autonomic nervous system , subclinical infection , neurotoxicity , peripheral nervous system , heart rate variability , lead (geology) , sympathetic nervous system , endocrinology , zinc , toxicity , central nervous system , anesthesia , physiology , heart rate , blood pressure , chemistry , biology , organic chemistry , paleontology
Quantitative assessment of the autonomic neurotoxicity due to lead was undertaken by measuring variability in the electrocardiographic R‐R interval (CV RR ) in 16 male workers exposed to lead, zinc, copper, and tin and in 16 unexposed control subjects. Two component coefficients of variation in the R‐R interval, the C‐CV RSA (respiratory sinus arrhythmia) and C‐CV MWSA (Mayer wave related sinus arrhythmia), were examined; these indices are considered to reflect parasympathetic and sympathetic activities, respectively. Maximal motor and sensory conduction velocities (MCV and SCV) in the median nerve were also measured. In the 16 exposed workers, blood lead concentrations ranged from 16 to 60 (mean 34) pg/dl. The CV RR and C‐CV RSA were found to be significantly reduced in the workers with elevated lead, zinc, and copper absorption as compared to unexposed control subjects; also, the MCV and SCV were significantly slowed. The C‐CV MWSA was not significantly reduced, and was positively related to plasma zinc concentrations. No significant relationships were found between indicators of lead and copper absorption and these electrophysiological measurements. These data suggest that subclinical toxicity of lead occurs in the parasympathetic component of the autonomic nervous system as well as in the peripheral nerves. Zinc may antagonize the autonomic nervous dysfunction caused by lead.