Calcium Waves in Retinal Glial Cells

Abstract

Calcium signals were recorded from glial cells in acutely isolated rat retina to determine whether Ca 2+ waves occur in glial cells of intact central nervous system tissue. Chemical (adenosine triphosphate), electrical, and mechanical stimulation of astrocytes initiated increases in the intracellular concentration of Ca 2+ that propagated at ∼23 micrometers per second through astrocytes and Müller cells as intercellular waves. The Ca 2+ waves persisted in the absence of extracellular Ca 2+ but were largely abolished by thapsigargin and intracellular heparin, indicating that Ca 2+ was released from intracellular stores. The waves did not evoke changes in cell membrane potential but traveled synchronously in astrocytes and Müller cells, suggesting a functional linkage between these two types of glial cells. Such glial Ca 2+ waves may constitute an extraneuronal signaling pathway in the central nervous system.