当前位置： SCI文献检索 > PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA期刊下所有文献 > Functional dependence of Ca(2+)-activated K+ current on L- and N-type Ca2+ channels: differences between chicken sympathetic and parasympathetic neurons suggest different regulatory mechanisms.

Functional dependence of Ca(2+)-activated K+ current on L- and N-type Ca2+ channels: differences between chicken sympathetic and parasympathetic neurons suggest different regulatory mechanisms.

Abstract：

:The influx of Ca2+ ions controls many important processes in excitable cells, including the regulation of the gating of Ca(2+)-activated K+ channels (the current IK[Ca]). Various IK[Ca] channels contribute to the regulation of the action-potential waveform, the repetitive discharge of spikes, and the secretion of neurotransmitters. It is thought that large-conductance IK[Ca] channels must be closely colocalized with Ca2+ channels (ICa) to be gated by Ca2+ influx. We now report that IK[Ca] channels can be preferentially colocalized with pharmacologically distinct subtypes of voltage-activated Ca2+ channel and that this occurs differently in embryonic chicken sympathetic and parasympathetic neurons. The effects of various dihydropyridines and omega-conotoxin on voltage-activated Ca2+ currents (ICa) and Ca(2+)-activated K+ currents (IK[Ca]) were examined by using perforated-patch whole-cell recordings from embryonic chicken ciliary and sympathetic ganglion neurons. Application of nifedipine or omega-conotoxin each caused a 40-60% reduction in ICa, whereas application of S-(-)-BAY K 8644 potentiated ICa in ciliary ganglion neurons. But application of omega-conotoxin had little or no effect on IK[Ca], whereas nifedipine and S-(-)-BAY K 8644 inhibited and potentiated IK[Ca], respectively. These results indicate that IK[Ca] channels are preferentially coupled to L-type, but not to N-type, Ca2+ channels on chicken ciliary ganglion neurons. Chicken sympathetic neurons also express dihydropyridine-sensitive and omega-conotoxin-sensitive components of ICa. However, in those cells, application of omega-conotoxin caused a 40-60% reduction in IK[Ca], whereas nifedipine reduced IK[Ca] but only in a subpopulation of cells. Therefore, IK[Ca] in sympathetic neurons is either coupled to N-type Ca2+ channels or is not selectively coupled to a single Ca(2+)-channel subtype. The preferential coupling of IK[Ca] channels with distinct ICa subtypes may be part of a mechanism to allow for selective modulation of neurotransmitter release. Preferential coupling may also be important for the differentiation and development of vertebrate neurons.

journal_name

Proc Natl Acad Sci U S A

journal_title

Proceedings of the National Academy of Sciences of the United States of America

authors

Wisgirda ME,Dryer SE

doi

10.1073/pnas.91.7.2858

subject

Has Abstract

pub_date

1994-03-29 00:00:00

pages

2858-62

issue

eissn

0027-8424

issn

1091-6490

journal_volume

pub_type

杂志文章

在线工具

Functional dependence of Ca(2+)-activated K+ current on L- and N-type Ca2+ channels: differences between chicken sympathetic and parasympathetic neurons suggest different regulatory mechanisms.