DEXMEDETOMIDINE, A POTENT AND HIGHLY SPECIFIC ALPHA2 AGONIST, EVOKES CYTOSOLIC CALCIUM SURGE IN ASTROCYTES BUT NOT IN NEURONS

Dexmedetomidine is an extremely potent alpha2 adrenoceptor agonist which can reduce anaesthetic requirements by up to 90%. However, the precise cellular mechanism of action of this agent is not known. Primary cultures of murine neurons and astrocytes were grown to test the hypothesis that changes in free intracellular calcium may trigger cellular responses to this drug. In astrocyte cultures, experiments revealed a pronounced increase in cytosolic calcium concentration when 100 nM dexmedetomidine was administered. However, in cultured cerebellar granule cell neurons there was no calcium response observed with similar or even higher concentrations of the drug. Results suggest dexmedetomidine may exert its primary effect on the central nervous system via astrocytes.