FIG. 4.

Pretreatment of slices with 10 mM caffeine did not prevent the methylmercury (MeHg)-induced initial increase in frequency of spontaneous inhibitory postsynaptic currents (sIPSCs) in Purkinje cells. A–B, sIPSCs were recorded from a representative Purkinje cell in a slice at a holding potential of −60 mV in the presence of 10 µM 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) and 50 µM amino-5-phosphonopentanoic acid (APV). The slice was first incubated with 10 mM caffeine (Caff) in the bath for 15 min and then exposed to 20 μM MeHg plus 10 mM caffeine (MeHg+Caff) in 2 mM Ca²⁺-containing artificial cerebrospinal fluid (ACSF) for 5 min. C, Effect of MeHg on cumulative fraction of inter-event intervals of sIPSCs from the same cell shown in (A). Bin size: 100 ms. D, Effect of MeHg on amplitude distribution of sIPSCs from the same cell in (A). Bin size: 10 pA. E–F, Comparisons of MeHg effects on relative frequency or amplitude of sIPSCs in the presence of caffeine in regular ACSF. Each trace is a representative depiction of 6 individual experiments. The asterisk indicates a statistically significant difference between the 2 groups (P < .05).