Figure 2.

Cytoplasmic [Ca²⁺]_c and nuclear [Ca²⁺]_n rise in response to V₁ agonist in cortical astrocytes. Cortical astrocytes were loaded with fura-2, and Ca²⁺ images were recorded with the InCyt2 fluorescence imaging system. A, Fura-2-generated Ca²⁺ images under basal conditions and after addition of V₁ agonist for 100 sec. V₁ agonist induced a marked nuclear Ca²⁺ compartmentalization. Scale bar, 30 μm. B, Window apertures were used to locate the cytoplasm and nucleus of one representative astrocyte, and [Ca²⁺]_c and [Ca²⁺]_n were plotted against time. V₁ agonist was added where indicated and was present throughout the entire observation period. Note that Ca²⁺ was increased initially in both the cytoplasm and nucleus, followed by a rapid and transient Ca²⁺ localization into the nucleus. After the rise in [Ca²⁺]_n, translocation of nuclear Ca²⁺ back to the cytoplasm occur red before there turn to baseline total [Ca²⁺]_i.