Transitional changes in membrane potential and intracellular [Ca2+] in rat basophilic leukemia cells

Area of Science:

• Cellular physiology
• Ion channel function
• Calcium signaling

Background:

• Store-operated calcium entry (SOCE) is crucial for cellular functions.
• Thapsigargin is a known inhibitor of the sarco/endoplasmic reticulum Ca2+-ATPase (SERCA).
• Changes in membrane potential can influence intracellular calcium levels.

Purpose of the Study:

• To investigate the effects of thapsigargin-induced SOCE on membrane potential in rat basophilic leukemia cells.
• To examine the relationship between membrane potential changes and intracellular calcium ([Ca2+]i) dynamics during SOCE.
• To elucidate the mechanisms underlying the observed electrical and calcium transients.

Main Methods:

• Whole-cell current-clamp electrophysiology to measure membrane potential.
• Single-cell fura-2 fluorescence measurements to quantify intracellular calcium.
• Combined electrophysiology and calcium imaging in rat basophilic leukemia cells.

Main Results:

• Thapsigargin induced complex membrane potential changes, including depolarization and hyperpolarization shifts.
• SOCE activation was associated with a significant increase in [Ca2+]i.
• Approximately 60% of cells exhibited transient, abrupt declines in [Ca2+]i during the calcium influx.
• Observed [Ca2+]i changes correlated with the recorded membrane potential fluctuations.

Conclusions:

• Thapsigargin-mediated SOCE elicits complex membrane potential alterations in leukemia cells.
• The interplay between inwardly rectifying K+ conductance and an inward current contributes to these potential changes.
• Observed [Ca2+]i transients are consistent with the dynamic membrane potential shifts during SOCE.