Figure 8.
Stimulation with LPS primes cellular responses for following single or combined stimulation with HMGB1. Ca2+ imaging experiments were performed to test the effects of a first stimulation with LPS on responses upon following single or combined HMGB1 stimulation (A,C,E,G) and vice versa (B,D,F,H). Stimulation protocols are shown in (A) and (B). LPS was used as the first stimulus in (A); in (B) it was HMGB1. The percentage of responsive cells (n, white bars) out of all cells tested (N, grey) is visualized in (C,D). LPS pre treatment significantly increased the percentage of HMGB1-responsive cells (E) compared to (F). In contrast, the responsiveness to LPS was significantly reduced by the previous application of HMGB1 (D). The reaction pattern of responsive cells is summarized in (E,F), and representative examples of two responsive cells are presented in (G–H). Please note that some of the responsive cells reacted to several of the stimuli used with an increase in the intracellular calcium concentration. PBS was applied as control, while KCl (50 mM) was used to confirm neuronal viability. The numbers of investigated cultures and independent experiments are given in Table 3.