Induction of adaptive response to chronic environmental and occupational exposure to radiation

The paper summarizes results of medical examination of two groups of patients, the public members resided in high natural background radiation areas and occupationally irradiated nu-clear and health workers. Adaptive response to chronic exposure to radiation was found to last much time and, thus, its impact on the development of late health effects, including cancer, may be great. In vitro studies demonstrate that induction of adaptive response is the multistep process including the excision reparation of nucleotides, nonhomologous DNA ends joining, antioxidative system and cell cycle control factors. The review presents data on effects of low doses radiation of high or low relative radiation effectiveness(RBE). Some damaged peripheral blood lympho-cytes demonstrated increased radioresistance to high radiation doses, results of examinations of both the public members and professionals.

5-Hydroxytryptamine-induced calcium-channel gating in rainbow trout (Oncorhynchus mykiss) peripheral blood lymphocytes

The present study was conducted on peripheral blood lympho-cytes of rainbow trout (Oncorhynchus mykiss) to assess the role of 5-hydroxytryptamine (5-HT; ‘serotonin’) in calcium signalling. 5-HT-induced increases in intracellular free calcium concentrations, [Ca2+]i, and its action was mediated by 5-HT receptor subtype 3 (5-HT3), but not by 5-HT receptor subtype 1A (5-HT1A) or subtype 2 (5-HT2) in these cells. In Ca2+-containing medium (1 mM CaCl2), 5-HT and 2-methyl-5-HT (5-HT3 receptor agonist) induced increases in [Ca2+]i, whereas in Ca2+-free medium (0 Ca2+, 1 mM EGTA), these two agents failed to evoke increases in [Ca2+]i in these cells, demonstrating that 5-HT mobilizes Ca2+ from the extracellular environment. Furthermore, 5-HT-induced increases in [Ca2+]i are not contributed to by the intracellular endoplasmic reticulum (ER) pool, as thapsigargin, an agent that recruits Ca2+ from ER stores, had additive effects on 5-HT-induced [Ca2+]i responses in fish peripheral lymphocytes. 5-HT-induced increases in [Ca2+]i were mediated by 5-HT3 receptors via gating the calcium through L-type, but not N-type, calcium channels in trout lymphocytes.