Elementary events of agonist-induced Ca2+ release in vascular endothelial cells |
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Authors: | Huser, Jorg Blatter, Lothar A. |
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Abstract: | The subcellular spatial and temporal organization ofagonist-induced Ca2+ signals wasinvestigated in single cultured vascular endothelial cells.Extracellular application of ATP initiated a rapid increase ofintracellular Ca2+ concentration([Ca2+]i)in peripheral cytoplasmic processes from where activation propagated asa[Ca2+]iwave toward the central regions of the cell. The average propagation velocity of the[Ca2+]iwave in the peripheral processes was 20-60 µm/s, whereas in thecentral region the wave propagated at <10 µm/s. The time course ofthe recovery of[Ca2+]idepended on the cell geometry. In the peripheral processes (i.e.,regions with a high surface-to-volume ratio)[Ca2+]ideclined monotonically, whereas in the central region[Ca2+]idecreased in an oscillatory fashion. Propagating[Ca2+]iwaves were preceded by small, highly localized[Ca2+]itransients originating from 1- to 3-µm-wide regions. The average amplitude of these elementary events ofCa2+ release was 23 nM, and theunderlying flux of Ca2+ amountedto ~1-2 × 1018mol/s or ~0.3 pA, consistent with aCa2+ flux through a single orsmall number of endoplasmic reticulum Ca2+-release channels. |
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