Fig. 4. Comparison of the effects of P2 receptor and gap junction blockade on the amplitude and efficacy of the Ca²⁺ signaling from neurons to satellite glial cells (SGCs) in trigeminal ganglion cultures.

Ca²⁺ signals were initiated by focal mechanical stimulation of a single neuron in Fura-2 AM loaded cultures and increases in intracellular Ca²⁺ levels in surrounding SGCs were recorded by epifluorescence. (A) Amplitude of the Ca²⁺ signal induced in SGCs in response to neuron stimulation and (B) efficacy of the neuron to SGC signaling (number of responding SGCs per total number of SGCs surrounding the stimulated neuron) determined in the absence (Control) and in the presence of either the broad-spectrum P2 receptor blocker suramin (Sur, 50 µM) or the gap junction blocker carbenoxolone (Carb, 100 µM). Note in suramin-treated cultures the significant reduction in the amplitude of SGC response to neuron stimulation, whereas carbenoxolone treatment had lesser effect. The efficacy of neuron to SGC signaling in suramin and in carbenoxolone-treated cultures was not significantly different from that observed in control conditions. Bars correspond to mean ± SEM; number of fields analyzed, 54 in control conditions, 9 in suramin- and 13 in carbenoxolone-treated cultures.