当前位置： SCI文献检索 > JOURNAL OF NEUROPHYSIOLOGY期刊下所有文献 > Ionic basis of the resting membrane potential and action potential in the pharyngeal muscle of Caenorhabditis elegans.

Ionic basis of the resting membrane potential and action potential in the pharyngeal muscle of Caenorhabditis elegans.

Abstract：

:The pharynx of C. elegans is a rhythmically active muscle that pumps bacteria into the gut of the nematode. This activity is maintained by action potentials, which qualitatively bear a resemblance to vertebrate cardiac action potentials. Here, the ionic basis of the resting membrane potential and pharyngeal action potential has been characterized using intracellular recording techniques. The resting membrane potential is largely determined by a K(+) permeability, and a ouabain-sensitive, electrogenic pump. As previously suggested, the action potential is at least partly dependent on voltage-gated Ca(2+) channels, as the amplitude was increased as extracellular Ca(2+) was increased, and decreased by L-type Ca(2+) channel blockers verapamil and nifedipine. Barium caused a marked prolongation of action potential duration, suggesting that a calcium-activated K(+) current may contribute to repolarization. Most notably, however, we found that action potentials were abolished in the absence of external Na(+). This may be due, at least in part, to a Na(+)-dependent pacemaker potential. In addition, the persistence of action potentials in nominally free Ca(2+), the inhibition by Na(+) channel blockers procaine and quinidine, and the increase in action potential frequency caused by veratridine, a toxin that alters activation of voltage-gated Na(+) channels, point to the involvement of a voltage-gated Na(+) current. Voltage-clamp analysis is required for detailed characterization of this current, and this is in progress. Nonetheless, these observations are quite surprising in view of the lack of any obvious candidate genes for voltage-gated Na(+) channels in the C. elegans genome. It would therefore be informative to re-evaluate the data from these homology searches, with the aim of identifying the gene(s) conferring this Na(+), quinidine, and veratridine sensitivity to the pharynx.

journal_name

J Neurophysiol

journal_title

Journal of neurophysiology

authors

Franks CJ,Pemberton D,Vinogradova I,Cook A,Walker RJ,Holden-Dye L

doi

10.1152/jn.00233.2001

subject

Has Abstract

pub_date

2002-02-01 00:00:00

pages

954-61

issue

eissn

0022-3077

issn

1522-1598

journal_volume

pub_type

杂志文章

在线工具

Ionic basis of the resting membrane potential and action potential in the pharyngeal muscle of Caenorhabditis elegans.