Calcium

Calcium is mentioned as a neuroregulator because there is evidence that inhaled anesthetics alter intracellular concentrations of calcium and because changes in intracellular calcium may influence neuronal excitability (e.g., by a calcium-dependent release of neurotransmitter).^[76] Inhaled anesthetics usually increase resting cytoplasmic calcium concentration, ^[76] and it has been proposed that the depressant action of halothane in rat hippocampal slices involves enhancement of GABA-mediated inhibition through release of intraneuronally stored calcium.^[77] In contrast, increases in intraneuronal calcium evoked by various stimuli are often prevented by inhaled agents. The mechanisms for the attenuation of the calcium increase by inhaled anesthetics may depend on the anesthetic and tissue examined and include impairment of calcium influx into cells^[76] and modulation of intracellular calcium release through action on inositol triphosphate-dependent pathways.^[78]