Abstract. Naphazoline nitrate is a medicine with a number of side effects, which should be taken into account not only in therapeutic practice, but also when developing preventive measures in pharmaceutical production. The purpose of our work was to study the effect of naphazoline nitrate on redox processes and the duration of survival of bull spermatozoa. Bull semen samples were divided into groups: control – without adding naphazoline nitrate and experimental – with adding naphazoline nitrate. The respiratory activity of spermatozoa was determined by the polarographic method, reducing capacity – potentiometrically, succinate dehydrogenase activity – photometrically; sperm survival – visually. The respiratory activity of spermatozoa is significantly inhibited under the effect of all studied doses of naphazoline nitrate (η = 0.762 and 0.840) and the degree of effect for the highest dose reaches 85.5 %. The reducing capacity changes significantly, starting from a dose of 1/10 LD50 and above, the dose-indicator correlation is low, the dose of LD50 causes changes in the indicator by 229.0% with a change of charge of the medium. SDH activity significantly decreases under the effect of 1/10 LD50 and above, the dose-indicator correlation is moderate, the dose of LD50 causes changes in the indicator by 49.5 %. The substance affects the duration of survival only in the maximum dose, reducing the survival time by 18 %. Conclusion: The substance has the maximum effect on the respiratory activity of germ cells and on the reducing capacity, it has a lesser effect on the SDH activity and slightly affects the survival time. The dose-dependent nature of the effect of naphazoline nitrate on certain indicators of redox processes in spermatozoa confirms the prospects of using the latter as alternative test objects in studying the harmful effects of chemicals.

Keywords: naphazoline nitrate, bull spermatozoa, redox processes