The TRPV4 agonist 4αPDD triggers Ca²⁺ oscillations in astrocytes of the hippocampal CA1 region.

<p>(<b>A–D</b>) Astrocytes in acute rat hippocampal slices loaded with the calcium fluorescent probe Fluo-4 AM respond with an increase in fluorescence to the application of the TRPV4 channel agonist 4αPDD (5 µM). (A) Cells before 4αPDD application in aCSF, (<b>B</b>) during 4αPDD application, (<b>C</b>) during 4αPDD application in aCSF without Ca²⁺ (aCSF_ØCa) and (<b>D</b>) during washout with aCSF. Note the increased fluorescence indicated by the arrow in B. (<b>E</b>) Cells loaded with Sulforhodamine 101 (SR-101) to verify that the measured cells are astrocytes. (<b>F</b>) Representative fluorescence traces with background correction of astrocytes in acute slices prepared from sham-operated rats (CTRL) and rats 1 hour (1H H/I) and 7 days (7D H/I) after hypoxia/ischemia. (<b>G</b>) Histogram of the mean intracellular calcium transients per hour before 4αPDD application (aCSF), during 4αPDD application (4αPDD), during 4αPDD application in aCSF_ØCa (4αPDD in aCSF_ØCa) and following washout (aCSF), measured in astrocytes from acute hippocampal slices prepared from the brains of sham-operated rats (CRTL) and those 1 hour (1H H/I) and 7 days (7D H/I) after hypoxia/ischemia. (<b>H</b>) Histogram of the number of responding cells (n = number of all analyzed cells). The values are presented as mean ± S.E.M. Statistical significance was calculated using one-way ANOVA. *p<0.05, significant; ***p<0.001, extremely significant.