Inhibitory effect of 1,1,1-trichloroethane on calcium channels of neurons.
Peripheral neuropathy may remain for some time after 1,1,1-trichloroethane exposure. A variety of Ca2+ channels gives sensory neurons many kinds of transmitting sensory information. We measured calcium currents in sensory neurons from neonatal rat dorsal root ganglion using whole-cell patch-clamp recordings. Trichloroethane reversibly reduced the low-voltage-activated (LVA) and high-voltage-activated (HVA) calcium. The half-inhibitory concentration (IC50) of the HVA and LVA currents was 5.76 x 10(-3) M and 3.99 x 10(-3) M, respectively. The Hill coefficient of the HVA and LVA currents was 0.61 and 1.04, respectively. In assessing voltage dependence for activation and inactivation of calcium currents, only the HVA calcium current was inactivated at greater negative potentials. This may be one of the mechanisms to reduce HVA current. However, activation and inactivation of the LVA currents were not affected by trichlorothane, so inhibition of the LVA currents may have other mechanisms. Calcium currents are thought to be involved in the control of neuronal excitability and neurotransmitter release. The inhibitory effect of trichloroethane on calcium currents may be involved in trichloroethane-induced sensory discomfort.
Okuda
M
M
Department of Public Health, Yamaguchi University School of Medicine, 1-1-1, Minamikogushi, Ube, Yamaguchi 755-8505, Japan.
Kunitsugu
I
I
Kobayakawa
S
S
Hobara
T
T
D000818:Animals; D000831:Animals, Newborn; D002121:Calcium Channel Blockers / Q000633:toxicity*; D015220:Calcium Channels / Q000502:physiology*; D004305:Dose-Response Relationship, Drug; D005727:Ganglia, Spinal / Q000187:drug effects / Q000502:physiology; D066298:In Vitro Techniques; D009475:Neurons, Afferent / Q000187:drug effects* / Q000502:physiology; D018408:Patch-Clamp Techniques; D051381:Rats; D012997:Solvents / Q000633:toxicity*; D014240:Trichloroethanes / Q000633:toxicity*
D002121:Calcium Channel Blockers; D015220:Calcium Channels; D012997:Solvents; D014240:Trichloroethanes; C024566:1,1,1-trichloroethane