Hyperthermal Influence on Intracellular Free Calcium Concentration in Cultured Macrophages of Mice.

Abstract

In this study, we have determined the fluorescence value of intracellular free calcium([Ca2+]i) in macrophages from mice cultured in different temperatures(37°C, 38°C and 39°C) by laser cytometer. The results indicate that hyperthermia caused elevations in the levels of [Ca2+]i. The characteristic effects of hyperthermia were, 1) rapid changes in [Ca2+]i concentration, that is to say, the fluorescence value of [Ca2+]i rose a few sec after hyperthermia; 2) a detectable relationship between the fluorescence value and temperature during defined temperature(38°C−39°C) and time(0−3600sec), 3) non−synchronous responses of cells, in other words, the extent and time of elevation of [Ca2+]i fluorescence value were different among the cells of the same group. We thought [Ca2+]i elevation induced by heat happened through the mechanism of IP3−induced calcium release(IICR) and calcium−induced calcium release(CICR). The heparin and procaine might lower the concentration of [Ca2+]i during hyperthermia through the mechanism that IICR and CICR were inhibited respectively. Free calcium influx from the extracellular medium was not thought to be necessary for heat−induced [Ca2+]i elevation.