Highly thermosensitive Ca2+dynamics in a HeLa cell through IP3receptors

Abstract

Intracellular Ca²⁺ distribution and its dynamics are essential for various cellular functions. We show with single HeLa cells that a microscopic heat pulse induces Ca²⁺ uptake into intracellular stores during heating and Ca²⁺ release from them at the onset of recooling, and the overshoot of Ca²⁺ release occurs above the critical value of a temperature change, which decreases from 1.5 to 0.2 ^°Con increasing the experimental temperature from 22 to 37 °C. This highly thermosensitive Ca²⁺ dynamics is probably attributable to the altered balance between Ca²⁺ uptake by endoplasmic reticulum Ca²⁺‐ATPases and Ca²⁺ release via inositol 1,4,5‐trisphosphate receptors. These results suggest that Ca²⁺ signaling is extremely sensitive to temperature changes, especially around body temperature, in cells expressing inositol 1,4,5‐trisphosphate receptors.