Faculty Collaboration Database

Na+ channel inactivation: a comparative study between pancreatic islet beta-cells and adrenal chromaffin cells in rat. J Physiol 2003 Apr 01;548(Pt 1):191-202

Date

02/11/2003

Pubmed ID

12576496

Pubmed Central ID

PMC2342793

DOI

10.1113/jphysiol.2002.034405

Scopus ID

2-s2.0-0037385010 (requires institutional sign-in at Scopus site)   33 Citations

Abstract

A comparative study was carried out on the inactivation of Na+ channels in two types of endocrine cells in rats, beta-cells and adrenal chromaffin cells (ACCs), using patch-clamp techniques. The beta-cells were very sensitive to hyperpolarization; the Na+ currents increased ninefold when the holding potential was shifted from -70 mV to -120 mV. ACCs were not sensitive to hyperpolarization. The half-inactivation voltages were -90 mV (rat beta-cells) and -62 mV (ACCs). The time constant for recovery from inactivation at -70 mV was 10.5 times slower in beta-cells (60 ms) than in ACCs (5.7 ms). The rate of Na+-channel inactivation at physiological resting potential was more than three times slower in beta-cells than in ACCs. Na+ influx through Na+ channels had no effect on the secretory machinery in rat beta-cells. However, these 'silent Na+ channels' could contribute to the generation of action potentials in some conditions, such as when the cell is hyperpolarized. It is concluded that the fractional availability of Na+ channels in beta-cells at a holding potential of -70 mV is about 15 % of that in ACCs. This value in rat beta-cells is larger than that observed in mouse (0 %), but is smaller than those observed in human or dog (90 %).

Author List

Lou XL, Yu X, Chen XK, Duan KL, He LM, Qu AL, Xu T, Zhou Z

Author

Xuelin Lou PhD Professor in the Cell Biology, Neurobiology and Anatomy department at Medical College of Wisconsin

MESH terms used to index this publication - Major topics in bold

Adrenal Glands
Animals
Cells, Cultured
Chromaffin Cells
Electrophysiology
Islets of Langerhans
Kinetics
Membrane Potentials
Mice
Patch-Clamp Techniques
Rats
Rats, Wistar
Sodium Channel Blockers
Tolbutamide