The dissertation is devoted to the study of ion-transporting (Ca2+ -transients and ATP-dependent systems) and free radical processes (indicators of prooxidant manifestations, glutathione antioxidant system and L-arginine/NO system) in spermatozoa of infertile men with different forms of pathospermia. It was found that spermatozoa of men with oligozoospermia and leukocytospermia have reduced sensitivity to physiological
(progesterone) and pharmacological agents (K+ channel blockers). Mitochondria in the sperm cells of infertile men showed decrease in the peak amplitudes of the CCCP-induced [Ca2+]i-transient after decrease in the progesterone-induced peak [Ca2+]i-transient, indicating impaired mitochondrial calcium-regulating function. Pathospermia has been found to be associated with impaired ATPe-induced [Ca2+]i-transients in sperm and a significant decrease in Ca2+ accumulation capacity of infertile men's sperm mitochondria, which may adversely affect the processes of spermatozoa activation and result in disorders of fertilisation.
The inhibition of ouabainensitive Na+, K+-ATPase activity and decrease in the activity of tapsigargin-sensitive and tapsigargin-resistant components of Ca2+, Mg2+ -ATPases of spermatozoa in men with astheno-, oligoasthenozoospermia and leukocytospermia compared to normozoospermic samples was detected. In spermatozoa of oligo- and leukocytospermic men, the transport of Na+ and K+ ions through the plasma membrane occurs more slowly and less actively than in normozoospermic sperm cells, but is characterized by almost the same capacity. However, in spermatozoa of infertile men with reduced mobility, transportation of Na+ and K+ ions through the plasma membrane is
characterized by reduced capacity. It was determined that inhibition of Na+, K+-ATPase activity in spermatozoa of infertile men occurs not by reducing the reaction rate, but by reducing the affinity for ATP.
The biochemical mechanisms of decrease in ion-transporting ATP-hydrolysis systems under conditions of H2O2-induced oxidative stress were found. It was revealed that under conditions of H2O2-induced oxidative stress, inhibition of Na+, K+ -ATPase
activity in spermatozoa occurs by reducing the enzyme affinity to the substrate and the reaction rate (only for normozoospermic samples). Inhibition of Ca2+, Mg2+-ATPases was associated with decrease in the maximum rate of the ATP-hydrolase reaction, without changing the enzyme affinity to Ca2+ ions.
The increase in TBARS content, inhibition of glutathione enzymes activity of antioxidant defense, decrease in content and redox glutathione index in spermatozoa of infertile men compared to fertile men were found. According to the ratio of indicators of the state of antioxidant factors (glutathione peroxidase activity, glutathione reductase and glutathione-S-transferase, GSH content) and prooxidant manifestations (TBARS and
GSSG), the indicators of antioxidant status were determined and pathological coherence was found out: oligozoospermia >> oligoastenozoospermia >> astenozoospermia >> leukocytospermia.
The effect of radical (O2•-- generating system Fe3+/ascorbate) and non-radical (H2O2) ROS on glutathione -S- transferase activity and the content of lipid peroxidation products in the spermatozoa of fertile and infertile men was determined and it was revealed that inhibitory effect of O2•-generating system was higher than non-radical types of ROS.
The redistribution of NO-synthase activity with shift toward the Ca2+-independent inducible isoform and inhibition of the arginine pathway of L-arginine metabolism in the infertile men’s spermatozoa, which were not significantly dependent on the type of spermatogenesis disturbance, was revealed. The biochemical mechanisms of cNOS inhibition were investigated and it was found out that in oligozoospermia cNOS activity
suppression is due to the increase in affinity to the substrate, and in asthenozoospermia both by reducing the affinity of the enzyme to the substrate and by reducing the reaction rate.
