Photolytic flash-induced intercellular calcium waves using caged calcium ionophore in cultured astrocytes from newborn rats

Iwabuchi, Sadahiro; Kikuchi, Kôichi; Makisaka, Koji; Sato, Hideomi

doi:10.1007/s00221-002-1311-6

Cited by 1 publication

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“…Uncaging IP 3 was shown to result in robust Ca 2+ increases in the patch‐clamped astrocyte, but failed to propagate to adjacent cells despite the extensive coupling of the patched cell to astrocytes throughout the hippocampus. However, in cultured astrocytes, focal photolysis of caged Ca 2+ ionophore in cultured rat astrocytes was found to result in an increase in intracellular Ca 2+ in a single astrocyte, and this increase was reported to propagate to neighboring astrocytes (Iwabuchi et al . 2002).…”

Section: Discussionmentioning

confidence: 99%

Glutamate pretreatment affects Ca²⁺ signaling in processes of astrocyte pairs

Padmashri

Sikdar

2006

Journal of Neurochemistry

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Simultaneous somatic patch-pipette recording of a single astrocyte to evoke voltage-gated calcium currents, and Ca 2+ imaging, were used to study the spatial and temporal profiles of depolarization-induced changes in intracellular Ca 2+ ([Ca 2+ ] i ) in the processes of cultured rat cortical astrocytes existing as pairs. Transient Ca 2+ changes locked to depolarization were observed as microdomains in the processes of the astrocyte pairs, and the responses were more pronounced in the adjoining astrocyte. Considering the functional significance of higher concentrations of glutamate observed in certain pathological conditions, Ca 2+ transients were recorded following pretreatment of cells with glutamate (500 lM for 20 min). This showed distance-dependent incremental scaling and attenuation in the presence of the metabotropic glutamate receptor (mGluR) antagonist, a-methyl(4-carboxy-phenyl) glycine (MCPG Glutamate is the major excitatory neurotransmitter in the mammalian central nervous system. Brain extracellular glutamate concentrations are approximately 2 lM, while cytosolic glutamate ranges from 1 to 10 mM (Erecinska and Silver 1990). Clearance of glutamate from the extracellular space is accomplished primarily by a family of Na + -dependent, high affinity glutamate transporters with the GLAST and GLT-1 subtypes being expressed in the astrocytes (Gegelashvili and Schousboe 1998). Neurological conditions, such as stroke, hypoxia/ischemia and hypoglycemic insults, result in higher concentrations of glutamate in the extracellular space (Greene and Greenamyre 1996). Glutamate and its receptors are key molecular elements at the interface between neurons and glia. Physiological, molecular and biochemical studies have shown that both ionotropic and metabotropic glutamate receptors are present in glial cells in vivo (Steinhauser and Gallo 1996). Astrocytes respond to glutamate application with an increase in cytoplasmic free calcium that is propagated as calcium waves within the cytoplasm of individual astrocytes and adjacent astrocytes in a syncytium (CornellBell et al. 1990). Glutamate has been shown to cause an accumulation of inositol phosphates, in a time-and concentration-dependent manner, in cultured rat astroglial cells (Milani et al. 1989) through metabotropic receptor activation (Liu et al. 1997). Pre-incubation of astrocyte cultures with glutamate produces a dose-dependent increase in glutamate uptake (Duan et al. 1999

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Section: Discussionmentioning

confidence: 99%