Functional Consequences of Chemical Modification of the Saxitoxin Binding Site on Neuronal Sodium Channels
Abstract
Sodium channels for rat brain have been studied at the single channel level in planar bilayer membranes and by using sodium 22 tracer flux and tritium STX binding methods. The rate of ion movement through the open pore and chemical modification of a specific saxitoxin blocking site at the external mouth of the pore led to a rate theory model of sodium influx and calcium block of the channel. Modulation of the channels by saxitoxin, batrachotoxin and scorpion and sea anemone polypeptide toxins was investigated using single channel analysis. The modulation of sodium channel gating by external and internal divalent cations was evaluated, leading to a novel theory of voltage-dependent channel gating. Saxitoxin-sensitive and insensitive sodium channels were studied in cultures of rat brain glial cells (astrocytes). The expression of sodium channels with high affinity for saxitoxin occurs spontaneously in culture but can be prematurely initiated by growth hormones. Keywords: Ion channels, Neurotoxins, Gonyalux, Veratridine.
Document Details
- Document Type
- Technical Report
- Publication Date
- Apr 25, 1989
- Accession Number
- ADA211274
Entities
People
- Bruce K. Krueger
- Robert J. French
Organizations
- University of Maryland School of Medicine