Functional characterization of Ca²⁺-induced Cl⁻ responses of TG neurons.

<p>A–C show results of Cl⁻ imaging experiments. With the exception of E, all experiments were performed on newborn mouse neurons. A, B: 100 µM ATP-stimulated Cl⁻ efflux in TG neurons in the presence and absence of extracellular Ca²⁺ (n = 18). C: Quantification of neurons displaying either a decrease, an increase, or no alteration of [Cl⁻]_i upon ATP stimulation (n = 76). D–J show results of Ca²⁺ imaging experiments. Representative Ca²⁺ responses of a newborn (D, n = 1178) and adult mouse TG neuron (E, n = 169) to stimulation with saturating concentrations of GABA (250 µM) and capsaicin (3.3 µM). F: Mean Ca²⁺ response amplitudes to 3.3 µM capsaicin in saline containing 140 mM or 6 mM [Cl⁻] (n = 42). G: Percentage of WT (n = 62) and NKCC1^−/− (n = 101) TG neurons responsive to capsaicin. H: Mean Ca²⁺ response amplitudes to 3.3 µM capsaicin in WT (n = 62) and NKCC1^−/− (n = 101) TG neurons. I: Effects of the CaCC blockers DIDS (100 µM) and NFA (500 µM) on the mean amplitudes of 3.3 µM capsaicin-induced Ca²⁺ responses in WT TG neurons. J: Effects of NFA treatment on depolarization-induced Ca²⁺ responses of TG neurons (n = 94). K–M: Patch clamp characterization of capsaicin-induced responses. K: Exemplary response of a TG neuron to capsaicin in the presence and absence of 500 µM NFA (n = 9, p≤0.01). L: Effect of NFA on the capsaicin-induced current of a TG neuron in the absence of extracellular Ca²⁺ (n = 12, n. s.). M: Effect of NFA on the capsaicin-induced current of a HEK/mTRPV1 cell (n = 10, n. s.). * indicates significance at p≤0.05, and *** at p≤0.001.