ATP-dependent accumulation and inositol trisphosphate- or cyclic ADP-ribose-mediated release of Ca2+ from the nuclear envelope

Article Abstract:

Microscopic studies using fluorescent probes of the release and uptake of Ca2+ from cell nuclei in liver show that the Ca2+-sensitive fluorescent probe Fura 2 localizes mainly to the nuclear envelope, indicating that the inward and outward transport of Ca2+ from the nuclear envelope is responsible for the inositol triphosphate-dependent secretion of Ca2+. Fluorescent Ca2+ indicator-tagged dextrans display a uniform distribution in the nucleoplasm, while variations in external Ca2+ alter the nucleoplasmic Ca2+ level. Ca2+ released from the nuclear envelope enters nucleoplasm and diffuses out through nuclear pore complexes.

Biological transport, Calcium in the body, Calcium (Nutrient)

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Ca2+ flow via tunnels in polarized cells: recharging of apical Ca2+ stores by focal Ca2+ entry through basal membrane patch

Article Abstract:

The Ca2+ flow through tunnels in polarized cells is investigated. Capacitive Ca2+ entry is fully activated via sustained supramaximal agonist simulation. Ca2+ store depletion-induced focal Ca2+ entry via a point on the basal membrane is shown to be capable of recharging Ca2+ stores in the apical pole of pancreatic acinar cells. Elevation of Ca2+ is not detected during the recharging period. The process is completely dependent on a thapsigargin-sensitive Ca2+ ATPase in the endoplasmic reticulum.

Calcium channels, Cell interaction, Cell interactions

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Inositol triphosphate and cyclic ADP-ribose-mediated release of Ca2+ from single isolated pancreatic zymogen granules

Article Abstract:

Inositol triphosphate (IP3) and cyclic ADP-ribose (cADPr) evoke a marked decrease in the free calcium concentration inside zymogen granules (ZG) of pancreatic acinar cells. Using confocal microscopy, it has been shown that IP3 and cADPr induce the rapid release Ca2+ from the granules. A novel high resolution method further showed that IP3-mediated Ca2+ release causes a spike in cytosolic Ca2+ generation outside the ZG.

Pancreas

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