Enhanced survival of lethally irradiated adenosine A(3) receptor knockout mice. A role for hematopoietic growth factors?
Adenosine A(3) receptor knockout (A(3)AR KO) mice and their wild-type (WT) counterparts were compared from the point of view of their abilities to survive exposures to lethal doses of gamma-radiation belonging to the range of radiation doses inducing the bone marrow acute radiation syndrome. Parameters of cumulative 30-day survival (experiment using a midlethal radiation dose) or cumulative 11-day survival (experiment using an absolutely lethal radiation dose), and of mean survival time were evaluated. The values of A(3)AR KO mice always reflected their higher survival in comparison with WT ones, the P values being above the limit for statistical significance after the midlethal radiation dose and standing for statistical significance after the absolutely lethal radiation dose. This finding was considered surprising, taking into account the previously obtained findings on defects in numbers and functional properties of peripheral blood cells in A(3)AR KO mice. Therefore, previous hematological analyses of A(3)AR KO mice were supplemented in the present studies with determination of serum levels of the granulocyte colony-stimulating factor, erythropoietin, and thrombopoietin. Though distinct differences in these parameters were observed between A(3)AR KO and WT mice, none of them could explain the relatively high postirradiation survival of A(3)AR KO mice. Further studies on these mice comprising also those on other than hemopoietic tissues and organs can help to clarify their relative radioresistance.