Blockade by MPTP of the nicotinic acetylcholine receptor channels in embryonic Xenopus muscle cells.
The effects of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) on nicotinic acetylcholine (ACh) receptor channels were studied in cultured myocytes of 1-day-old Xenopus embryos. The amplitude and decay time of iontophoretic ACh-induced currents were reduced by MPTP in a concentration-dependent manner. The inhibitory action of MPTP was frequency-dependent, being enhanced by higher frequencies of stimulation at 7 and 30 Hz. Neither pargyline nor tranylcypromine affected the inhibitory effects of MPTP on ACh-induced currents. Single channel recordings showed that MPTP decreased the opening frequency, mean open time as well as the conductance of both low- and high-conductance ACh channels. These results suggest that the inhibitory actions of MPTP on ACh receptor channels in skeletal muscle may contribute to the depression of the nerve-evoked contraction of the mouse diaphragm as previously reported.
Hsu
K S
KS
Institute of Pharmacology, College of Medicine, National Taiwan University, Taipei.
Fu
W M
WM
Lin-Shiau
S Y
SY
D015632:1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine / Q000494:pharmacology*; D000818:Animals; D002478:Cells, Cultured; D018680:Cholinergic Antagonists; D004594:Electrophysiology; D007473:Ion Channels / Q000187:drug effects; D007478:Iontophoresis; D007700:Kinetics; D009132:Muscles / Q000187:drug effects / Q000378:metabolism*; D014981:Xenopus
D018680:Cholinergic Antagonists; D007473:Ion Channels; D015632:1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine