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The action potential of chick dorsal root ganglion neurones maintained in cell culture.
Author(s) -
Dichter M A,
Fischbach G D
Publication year - 1977
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1113/jphysiol.1977.sp011813
Subject(s) - depolarization , dorsal root ganglion , tetrodotoxin , extracellular , neuroscience , spike potential , membrane potential , biophysics , chemistry , sensory neuron , hyperpolarization (physics) , ganglion , biology , anatomy , spinal cord , sensory system , microbiology and biotechnology , organic chemistry , nuclear magnetic resonance spectroscopy
1. The directly evoked action potential of dissociated, embryonic, chick, dorsal root ganglion (DRG) neurones maintained in cell culture is prolonged compared to spinal cord cell spikes and the re‐polarization phase is marked by a plateau. 2. Evidence was obtained that both Ca2+ and Na+ carry inward current across the active soma membrane. Ca2+ because: overshooting spikes persist in tetrodotoxin (TTX) or Na+‐free media; in the presence of TTX (or absence of Na+) spike size varies directly with extracellular Ca2+ and spikes are eliminated by Co2+. Na+ because: spikes persist in the presence of Co2+ or Ca2+‐free media; in the presence of Co2+ (or absence of Ca2+) spike varies directly with extracellular Na+ and spikes are blocked by TTX. 3. On the other hand, Ca2+ plays less if any role in action potentials conducted along sensory nerve cell processes. Conducted spikes could not be evoked in TTX containing or Na+‐free media. 4. A long‐lasting depolarization follows the action potential in some neurones. This depolarization is associated with an increase in membrane conductance and appears to drive the membrane potential to ca. ‐30mV. It persists when conducted impulses are blocked so it is probably not a recurrent synaptic potential. 5. It is suggested that combined Ca2+‐Na+ spikes observed in isolated sensory neurones in vitro reflect the action potential of adult sensory cells but the possibility that they represent an early stage in development is also discussed.