Modulation of Radioprotective Effects of Respiratory Hypoxia by Changing the Duration of Hypoxia before Irradiation and by Combining Hypoxia and Administration of Hemopoiesis-Stimulating Agents

Abstract

The data presented confirm the radioprotective effect of 10% and 8% O2 respiratory hypoxia on hemopoiesis. These findings may represent a way out for further experimental and clinical research aimed at considering differential protection of various tissues by hypoxia.

Influence of the Leaf Extract of Mentha arvensis Linn. (Mint) on the Survival of Mice Exposed to Different Doses of Gamma Radiation

“…Therapeutic differential may be achieved with chemical radiation sensitizers or protectors. The development of radiation protectors is important not only to enhance the effectiveness of cancer treatment but also for the study of the underlying mechanisms of radiation cytotoxicity [7,49]. Some radioprotectors are known to protect by a direct effect on the cellular targets of radiation, while others protect by enhancing the recovery of normal tissues [11].…”

Preoperative Hypoxyradiotherapy of Colorectal Carcinoma

“…Specifically, the effect of hypoxia-induced radioprotection is highest during the first few minutes of hypoxia and decreases thereafter as a consequence of the adaptive changes in cell metabolism caused by hypoxia [30,32,33].…”

“…Since tumor tissue is usually chronically hypoxic, the induction of acute hypoxia during radiotherapy has only a selective radioprotective effect on noncancerous, normoxic tissues, especially hemopoietic and intestinal tissues [30]. Theoretical assumptions of differential radioprotection by acute hypoxia to tumor and normal tissues have been verified experimentally [17,22,33,39] as well as clinically [1,23,24,[25][26][27][28].…”

Hypoxic Versus Normoxic External-Beam Irradiation of Cervical Carcinoma Combined with Californium-252 Neutron Brachytherapy

“…Since tumor tissue is usually chronically hypoxic, the induction of acute hypoxia during radiotherapy causes a selective radioprotective effect only in noncancerous, normoxic tissues, especially in hemopoietic and intestinal tissues [46]. Theoretical assumptions of differential radioprotection by acute hypoxia to tumor and normal tissues have been verified experimentally [21,29,45,52], as well as clinically [1,28,30,37,40,42,43].…”

“…Specifically, hypoxia-induced radioprotection is most effective during the first several minutes of hypoxia and decreases thereafter. This diminishing protective effect is a consequence of the adaptive changes in cell metabolism caused by the hypoxia [46,51,52].…”