Figure 4.

Anandamide activation of VR1 is concentration-dependent, but less efficacious than capsaicin. Selected trigeminal neurons were voltage clamped at +40 mV, as described in Methods. Concentration-response curves for capsaicin and AEA to activate VR1 in trigeminal neurons. In each cell, capsaicin or AEA responses were normalized to that produced by 10–30 μM capsaicin in that cell. The EC₅₀ for capsaicin was 300 nM, for AEA 3 μM. AEA produced maximal currents 38±2% of maximal capsaicin currents. Each point represents the mean±s.e.mean of at least six cells, error bars are contained within the symbol for several points.