TRPV4 and Stroke: PID is a whole‐cell fluctuation that contributes to secondary infarct growth and negatively affects stroke outcome.[47, 48] This type of astrocytic Ca2+ signaling is increased at 1–2 h after a photothrombotic stroke in both the ischemic core and the penumbra.[49] The PID‐related astrocytic Ca2+ signals are contributed by IP3R2‐gated Ca2+ release from the endoplasmic reticulum and Ca2+ influx through the TRPV4 channels from the extracellular medium.