Glial cell swelling - Effect of hypothermia

The effect of mild to moderate hypothermia (32/27 degrees C) was analyzed o n the cell volume of C6 glioma cells and primary cultured astrocytes at nor mal pH, during lactacidosis (pH 6.2) and during exposure to glutamate or ar achidonic acid in vitro. The cells were suspended in an incubation chamber under continuous control of pH, pO(2) and temperature. Cell swelling was qu antified by an advanced Coulter-system. Following a control period at 37 de grees C, the ambient temperature was decreased to 27 and 32 degrees C for 3 0 min. Hypothermia alone led to an immediate and significant cell volume in crease of 107.3 +/- 0.4% (mean +/- SEM) of control after 30 min at 32 degre es C. Yet, hypothermia (27 degrees C) afforded partial protection against t he acidosis-induced cell swelling at pH 6.2, attaining 120.4 +/- 0.9% in th e normothermic control group after 60 min, while only 111.3 +/- 0.9% at 27 degrees C. Hypothermia, however, was not associated with a reduction of the glutamate- or arachidonic acid-induced cell swelling. The results demonstrate that mild hypothermia per se induces glial cell swe lling, but simultaneously inhibits cell swelling from acidosis, while not f rom glutamate- or arachidonic acid.