[The methodological aspects of the nonmonotonous dose-response dependence].

The methodological foundations of two radiobiological conceptions, the target-theory and the structural-metabolic theory in radiobiology, are discussed. According to the target theory the biologically significant structure (target size) exists in cell, and the dose-response dependence is monotonic. In the structural-metabolic theory, the target appears as the unity of the structure and metabolism. The role of homeostatic mechanisms in nonmonotonic metabolic time-course responses is discussed. The nonmonotonous dose-response dependence of functional and metabolic parameters is due to the nonmonotonous character of time-course response to ionizing radiation.