Fig. 1.

A, [³H]DPN-specific binding in primary sensory neurons reaches a maximal value of 725 fmol/mg protein by 9 days in culture. Values are expressed as mean ± S.E. (n = 3). Nonspecific binding was determined in the presence of 10 μM naltrexone. B, saturation binding isotherm for specific [³H]RTX in cultured (7-day) neonatal rat DRG neuron cell membranes (n = 3). Specific binding was obtained by subtracting total [³H]RTX binding (0.1–5 nM) from [³H]RTX binding in presence of 10 μM unlabeled resiniferatoxin (nonspecific binding).