Calcium signal dynamics in T lymphocytes: Comparing in vivo and in vitro measurements.

Amplitude and kinetics of intracellular Ca signals ([Ca]) determine many immune cell functions. To mimic in vivo changes of [Ca] in human immune cells, two approaches may be best suited: 1) Analyze primary human immune cells taken from blood under conditions resembling best physiological or pathophysiological conditions. 2.

Electrochemical Quantification of Extracellular Local HO Kinetics Originating from Single Cells.

Aims: HO is produced by all eukaryotic cells under physiological and pathological conditions. Due to its enormous relevance for cell signaling at low concentrations and antipathogenic function at high concentrations, precise quantification of extracellular local hydrogen peroxide concentrations ([HO]) originating from single cells is required.

Results: Using a scanning electrochemical microscope and bare platinum disk ultramicroelectrodes, we established sensitive long-term measurements of extracellular [HO] kinetics originating from single primary human monocytes (MCs) ex vivo.

Differential redox regulation of ORAI ion channels: a mechanism to tune cellular calcium signaling.

Reactive oxygen species (ROS) are involved in many physiological and pathophysiological cellular processes. We used lymphocytes, which are exposed to highly oxidizing environments during inflammation, to study the influence of ROS on cellular function. Calcium ion (Ca(2+)) influx through Ca(2+) release-activated Ca(2+) (CRAC) channels composed of proteins of the ORAI family is essential for the activation, proliferation, and differentiation of T lymphocytes, but whether and how ROS affect ORAI channel function have been unclear.

Inhibition of protein tyrosine phosphatase 1B by reactive oxygen species leads to maintenance of Ca2+ influx following store depletion in HEK 293 cells.

Depletion of inositol 1,4,5 trisphosphate-sensitive Ca2+ stores generates a yet unknown signal, which leads to increase in Ca2+ influx in different cell types [J.W. Putney Jr.

Hormone-stimulated calcium release is inhibited by cytoskeleton-disrupting toxins in AR4-2J cells.

We have studied the role of the actin cytoskeleton in bombesin-induced inositol 1,4,5-trisphosphate (IP(3))-production and Ca(2+)release in the pancreatic acinar tumour cell line AR4-2J. Intracellular and extracellular free Ca(2+)concentrations were measured in cell suspensions, using Fura-2. Disruption of the actin cytoskeleton by pretreatment of the cells with latrunculin B (10 microM), cytochalasin D (10 microM) or toxin B from Clostridium difficile (20 ng/ml) for 5-29 h led to inhibition of both, bombesin-stimulated IP(3)-production and Ca(2+)release.