Vol. 278, Issue 1, C26-C32, January 2000
Retardation of cation channel deactivation by mitochondrial
dysfunction in adrenal medullary cells
M.
Inoue,
N.
Fujishiro, and
I.
Imanaga
Department of Physiology, School of Medicine, Fukuoka University,
Fukuoka 814-0180, Japan
The
mechanism for cyanide (CN) activation of a nonselective cation (NS)
channel coupled with a muscarinic receptor in a guinea pig chromaffin
cell was studied with the perforated-patch method. Bath application of
a protein kinase inhibitor resulted in a dose-dependent inhibition of
muscarine-induced current (IM) but had no apparent effect on the CN-induced current (ICN). On the
other hand, production of ICN occluded muscarine
activation of NS channels in an amplitude-dependent manner.
Deactivation of IM after washout was retarded while
ICN was also active, and the extent of the
retardation increased with an increase in the relative production of
ICN on muscarinic stimulation. Restoration of
Na+ pump activity from CN suppression was conspicuously
retarded below 19-20°C, and the apparent diminution of
IM and ICN after washout was
retarded in parallel with a decrease in temperature. The results
suggest that CN activation of NS channels is due to suppression of
deactivation of the channel.
muscarinic receptor; mitochondria; temperature; cyanide
