Pluronic F-127 affects the regulation of cytoplasmic Ca²⁺ in neuronal cells

Fura-2 is one of the most widely used cytoplasmic Ca²⁺ ([Ca ²⁺]_cyt) sensors. In studies using isolated dorsal root ganglion (DRG) neurons, the loading of Fura-2 AM is often facilitated by the use of pluronic F-127. In preliminary studies, we detected that the use of pluronic F-127 appeared to be affecting the depolarization-evoked [Ca²⁺] _cyt transient in DRG neurons. To determine whether this was the case, we conducted a systematic study. Adult rat DRG neurons were cultured, and their response to 50 mM KCl was measured in sister cultured cells (isolated on the same day) that were loaded with 5 μM Fura-2AM in the absence or in the presence of 0.02% pluronic F-127. In the absence of pluronic F-127, the KCl-evoked [Ca²⁺]_cyt transient changed with time, being wider on day 1 than on day 2 after plating. On day 2, the KCl-evoked [Ca ²⁺]_cyt transient was wider in neurons Fura-2 loaded in the presence of pluronic F-127. These results indicate that pluronic F-127 significantly alters depolarization-evoked [Ca²⁺]_cyt transients, which may reflect alteration in regulation of [Ca²⁺] _cyt in neuronal cells.