Patch clamp recording from the intact dorsal root ganglion

Abstract

A method for patch-clamp recording from intact dorsal root ganglion (DRG) cells in rat is described. The L 4 and L 5 DRGs with sciatic nerve attached were excised from rats (10–15 days old) and placed in a recording chamber after removing the ganglion sheath and dissolving the connective tissue with dilute collagenase. The somata of individual cells were exposed by gentle surface cleaning through a perfusion micropipette. Somata were classified as A β, A δ or C based on the cell size and the shape of the action potential (AP). Under current clamp, axonal conduction velocity (CV) was calculated from the distance between a stimulating electrode and the center of the ganglion divided by the latency of the AP elicited by stimulation of the sciatic nerve. CVs ranged from 0.2–0.8 m/s for C cells, 0.8–2.4 for A δ and 3.2–5.0 for A β cells. AP threshold occurred at a significantly more positive potential in C cells than in A δ and A β cells. Under voltage clamp, sodium currents were recorded from C cells. Both TTX-resistant (TTX-R) and TTX-sensitive (TTX-S currents) were demonstrated in the present study. The results demonstrate the feasibility of patch-clamp recording from intact, identified DRG cells in vitro.