Role of Ca2+ in activation of reactive oxygen species production in polymorphonuclear leukocytes during tumour growth in rats

• Published in: Luminescence Vol. 22; no. 3; pp. 199 - 205
• Main Authors: Pustovidko, A, Potselueva, M., Kochegarov, A., Evtodienko, Y.
• Format: Journal Article
• Language: English
• Published: Chichester, UK John Wiley & Sons, Ltd 01-05-2007
• Subjects: Animals; Calcium - metabolism; Calcium - physiology; calcium signalling; Cell Division; chemiluminescence; Kinetics; Male; Neoplasms, Experimental - metabolism; Neoplasms, Experimental - pathology; Neutrophils - metabolism; polymorphonuclear leukocytes; Rats; Rats, Wistar; reactive oxygen species; Reactive Oxygen Species - metabolism; Zajdela hepatoma
• ISSN: 1522-7235; 1522-7243; 1099-1271
• DOI: 10.1002/bio.949

The role of Ca2+ ions in PMA‐induced generation of reactive oxygen species (ROS) by polymorphonuclear leukocytes (PMNL) was studied during Zajdela hepatoma growth in the peritoneal cavity of rats. In PMNL from control healthy animals, a manifold Ca2+‐induced enhancement of ROS generation and its significant reduction in the presence of Ca2+ binding agent (BAPTA‐AM) were observed. In contrast, ROS generation by PMNL from tumour‐carrying animals dramatically increased in Ca2+‐free medium, being practically insensitive to the agents, which can increase or decrease intracellular Ca2+ levels. Free cytosolic Ca2+ ([Ca2+]i) in control PMNL was found to be relatively low (∼250 nmol/L), rising slowly after Ca2+ addition and further to two‐fold in the presence of Ca2+ and ionomycin in the incubating medium. Tumour growth in animals was accompanied with a significant [Ca2+]i elevation. In Ca2+‐free medium, [Ca2+]i elevation was up to 480 nmol/L in tPMNL with the additions of Ca+ and ionomycin as well as EGTA and ionomycin being able to increase [Ca2+]i to 700–900 nmol/L onward. It was concluded that a higher Ca2+ permeability of the plasma membrane and higher Ca2+ accumulation in intracellular pools of PMNL was developed at the advanced stages of malignant disease. These results indicate the primed state of circulating PMNL and the independence of PMA‐induced ROS generation at intra‐ and extracellular Ca2+ levels at the advanced stages of tumour growth in animals. Copyright © 2007 John Wiley & Sons, Ltd.