Fig. 1
NVC increases spontaneous excitability. A Representative voltage tracers of spontaneous APs. Blue represents control and red, NVC. Shaded area indicates Ca0.2. Each trace represents 160 s of continuous acquisition. B Violin density plots (shaded) showing total AP count at 100 s in Ca1.1 and Ca0.2. Paired values represented by connected open circles showing change in AP count following divalent switch from Ca1.1 to Ca0.2. Diamonds indicate mean values, solid Ca1.1 and open Ca0.2. Mean AP counts in control were 35 ± 15 in Ca1.1, increasing to 670 ± 170 in Ca0.2. NVC exposure increased AP counts in Ca1.1 to 448 ± 131 and 1002 ± 182 in Ca0.2. Two-way repeated measures (RM) ANOVA suggested no interaction between divalent reduction and NVC (F(1,45) = 0.099, P = 0.753). However, both divalents (P < 0.0001) and NVC (P = 0.017) independently increased AP counts. Post hoc testing with Sidak multiple comparisons reveals divalent change increased firing in both control (P = 0.001) and NVC (P = 0.004). NVC increased AP firing at Ca1.1 (P = 0.002) but not Ca0.2 (P = 0.190), N = 24 (control) and 23 (NVC), respectively. C Plot with individual values of RMP. RMP in control was -78.4 ± 1.5 mV in Ca1.1 and −75.7 ± 1.5 mV in Ca0.2. NVC treatment depolarized neurons to −72.1 ± 1.6 mV in Ca1.1 and −64.0 ± 2.3 mV in Ca0.2. Solid circles represent Ca1.1 and open circles, Ca0.2. Two-way RM ANOVA indicates that divalent reduction and NVC treatment interact to depolarize RMP (F (1,48) = 6.281, P = 0.016). Post hoc testing with Sidak multiple comparisons reveals that NVC depolarizes RMP at both Ca1.1 (P = 0.025) and Ca0.2 (P < 0.0001). N = 26 (control) and 24 (NVC). Solid diamonds with error bars represent mean ± SEM. Control indicated by blue and NVC, red. Statistically significant P-values in this figure and all others denoted by schema * < 0.05, ** < 0.01, *** < 0.001 and **** < 0.0001