Change of individual vascular endothelial calcium during hyperthermia

Cytoplasmic Ca2+ ions play an important role in response to thermal stimuli as they are actively involved in many cellular activities. In this study, the change of calcium ion concentration ([Ca2+]i) was investigated in individual rat heart vascular endothelial cells during hyperthermia using fluorescence microscopy. The intracellular Ca2+ concentration continuously increased as temperature rose from 37 to 45 °C, and the increase mainly occurred in cytoplasm. Large [Ca2+]i variations were found from cell to cell. Further examination suggested that such variations were related to the cell cycle; the intracellular Ca2+ concentration changed the least when endothelial cells were arrested in the G1/G0 phase. Hyperthermic treatment might be significantly improved by further understanding of the cytoplasmic Ca2+ ions regulated pathway responses to thermal stimuli at the cellular level.