PATCH-CLAMP RECORDING FROM THE INTACT DORSAL-ROOT GANGLION

A method for patch-damp recording from intact dorsal root ganglion (DR G) 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 recor ding chamber after removing the ganglion sheath and dissolving the con nective tissue with dilute collagenase. The somata of individual cells were exposed by gentle surface cleaning through a perfusion micropipe tte. Somata were classified as A beta, A delta 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 betwe en a stimulating electrode and the center of the ganglion divided by t he 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 delta and 3.2-5.0 for A beta cells. AP threshold occurred at a significantly more positi ve potential in C cells than in A delta and A beta cells. Under voltag e clamp, sodium currents were recorded from C cells. Both TTX-resistan t (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. (C) 1998 Elsevie r Science B,V.