Figure 4.

Effects of cessation of glutamatergic drug on capsaicin-induced intracellular calcium elevation in primary cultured DRG neurons. (A) Experimental design for recording capsaicin-induced calcium elevation after washout of glutamatergic drugs. (B, C) Cumulative frequency graph showing changes in the F340/F380 ratio induced by capsaicin after washout of glutamate and quisqualate. (D, E) Quantitative data showing changes in the F340/F380 ratio induced by capsaicin after washout of glutamatergic drugs. Data represent average of 50% of neurons, those with the largest capsaicin-induced calcium elevation. (F–H) Pharmacological analysis of quisqualate-induced depression of capsaicin response in primary cultured DRG neurons. (F) Concentration–response curves of capsaicin (0.03–3.0 μM) after washout of quisqualate. The average E_max for capsaicin (△F340/F380 ratio) in control group was defined as 100%. Summary of changes in E_max (G) and EC₅₀ (H). Data presented as mean ± SEM. *P < 0.05, **P < 0.01, ***P < 0.0001, significantly different from control, ††P < 0.01, significantly different as indicated.