Cytosolic calcium during glucose deprivation in hippocampal pyramidal cells of rats

Glucose deprivation (GD) results in a hyperpolarization by turning on a potassium conductance (g_K,GD) in hippocampal CA3 pyramidal cells. We used combined intracellular and microfluorometric recording techniques to evaluate whether g_K,GD is activated by a rise in the concentration of intracellular calcium ([Ca²⁺]_i). We found that the activation of g_K,GD is only followed, but not preceded by a rise in [Ca²⁺]_i. Furthermore, g_K,GD is not blocked by the sulfonylurea glibenclamide, a blocker of ATP-regulated potassium conductance. We conclude that activation of g_K,GD does not simply reflect breakdown of the calcium of ATP homeostasis, but on the contrary might represent an active restoring mechanism which delays the pathological consequences of sustained glucose deficiency.