Alterations in cellular calcium signalling in human lymphocytes after hypoxia

Mooren FC, Becker D, Lechtermann A, Fromme A, Rudack P, Thorwesten L, Völker K

Abstract in digital collection (conference)

Abstract

Microenvironmental changes in oxygen partial pressure, caused by both pathological, e.g. ischemia, or physiological conditions, e.g. exhaustive exercise, have important effects on cellular signal transduction. The aim of the repsent study was to determine the influence of hypoxia on cellular calcium signalling and proliferative activity in human lymphocytes. Human lymphocytes were isolated by density gradientcentrifugation. Cells were incubated in medium at 37°C either under normoxic (75\% N2; 5\% CO2; 20\% O2) or hypoxic (92\% N2; 5\% CO2; 3\% O2) conditions for up to 1 hour. After reoxygenation cellular free calcium concentration ([Ca2+]i) was determined spectrophotometrically using the calcium sensitive dye Fura-2. Cell proliferation was determined by fluorescent cell division tracking using the fluorescent dye carboxyfluorescein succinimidyl ester. Basal intracellular calcium concentration of cells after normoxic incubation was 25.8+1.2 nmol/l. In contrast, cellular calcium concentration increased in a time-dependent fashion up to 230.1+16.6 nmol/l after 1 hour under hypoxic conditions. Moreover, phytohemagglutinin (PHA) induced calcium transients decreased after hypoxia, while calcium mobilization via the CD3-receptor by OKT-3 was not affected. Performing the hypoxic incubation in calcium free medium or in the presence of lanthanum prevented the increase in basal calcium and restored the agonist induced calcium transients. The latter effect was also observed after pre-incubation of cells with a calpain inhibitor. Cell proliferation decreased linearly with time of hypoxic incubation. Hypoxia induced inhibition of cell proliferation was partially reversible after pre-incubation cells with a calpain inhibitor. In lymphocytes, hypoxia induced an increase of basal intracellular calcium preferentially by an influx of extracellular calcium. Furthermore, hypoxia inhibited differentially stimulus-induced intracellular calcium transients and cell proliferation. These effects seemed to be mediated specifically by a calcium dependent protease as indicated by the effects of the calpain inhibitor.

Details zur Publikation

Book title: Abstract Book
Release year: 2003
ISBN: 3-901709-11-8
Language in which the publication is written: English
Event: Salzburg
Link to the full text: http://www.ecss.de/ASP/EDSS/C08/08-0107.pdf