A.I. D-yachenko, Yu.A. Shulagin, E.V. Stepanov, A.G. Zizina

This experiment proved a possibility to use a laser-based spectral analysis for noninvasive estimation of biological effects of radiation exposure. Excretion of endogenous carbon monoxide in expired gas was measured. We described methods and facilities used for laser-based endogenous carbon monoxide analysis in expired gas. Developed CO analyzer including a middle infrared tunable diode laser is specified. Gas sampling includes expired gas and mixed gas from a chamber. Typical values of CO content in room air, mixed expired and alveolar air, endogenous component of CO are presented. We developed a mathematical model of gas exchange in a chamber with an animal. In non steady state conditions the model predicts О2 consumption and СО, СО2 production by an animal. Values of gas content in a chamber as well as gas flow through the chamber are used for this prediction. Experimental study of expired gas composition was performed for a control group and a radiation exposed testing group of monkeys. Each group included two Macaca mulatta monkeys. The test group was exposed with 1.2 Gy radiation dose produced by gamma-rays. CO excretion of animal increased on the 3rd day after radiation exposure and decreased on the 28ht day after exposure. The increase in CO excretion was induced by increased red cells hemoglobin destruction. This destruction reduced a number of red cells. So on the 28ht day after exposure a number of destructed red cells was reduced decreasing CO production. Consumption of oxygen and excretion of carbon dioxide did not change after the exposure. This technique of endogenous CO monitoring in expired gas and in hermetic chamber could be used for estimation of biological effects of radiation exposure in humans. The development can be used for patients undergoing therapeutic radiation exposure, victims of radiation exposure in atomic plants.