| Pain Research | ||
 Abdallah Hayar |
An improved method for patch clamp recording and calcium imaging of neurons in the intact dorsal root ganglion in rats |  Elie Al-Chaer |
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The
properties of dorsal root ganglion (DRG) neurons have been mostly investigated
in culture of dissociated cells, and it is uncertain whether these cells
maintain the electrophysiological properties of the intact DRG neurons. Few
attempts have been made to record from DRG neurons in the intact ganglion using
the patch clamp technique. In this study, rat DRGs were dissected and incubated
for at least 1 hour at 37ºC in collagenase (10 mg/ml). We used oblique
epi-illumination to visualize DRG neurons and perform patch clamp recordings.
All DRG neurons exhibited strong delayed rectifier potassium current and a high
threshold for spike generation (-15 mV) that rendered the cells very weakly
excitable, generating only one action potential upon strong current injection
(>300 pA). It is therefore possible that cultured DRG neurons, commonly used in
studies of pain processing, may be hyperexcitable because they acquired
"neuropathic" properties due to the injury induced by their dissociation.
Electrical stimulation of the attached root produced an antidromic spike in the
soma that could be blocked by intracellular hyperpolarization or high frequency
stimulation. Imaging intracellular calcium concentration with Oregon Green
BAPTA-1 indicates that antidromic stimulation caused a long-lasting increase in
intracellular calcium concentration mostly near the cell membrane. Our study
describes a simple approach to examine the electrophysiological and
pharmacological properties and intracellular calcium signaling in DRG neurons in
the intact ganglion where the effects of somatic spike invasion can be studied
as well.
Hayar A, Gu C, Al-Chaer ED (2008) An improved method for patch clamp recording and calcium imaging of neurons in the intact dorsal root ganglion in rats. J Neurosci Methods 173:74-82. (Abstract) (PDF, 943 KB).
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