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In the protein-deficient media plasminogen stimulated the vital functions of cells and in concentrations 10(-7)-10(-10) M it protected cells of sympathetic ganglia, neocortex and continues cell lines under damaging actions of H2O2 (0.0001 M), NH4CI (0.01 M) and cooling. Streptokinase essentially influenced the mode of damaging effect of ATP(0.001 M). Even a short-term exposition (20 min) of PC12 cells with both proteins (each in the concentration 10(-9) M) led to sharp alterations in intracellular ATP- or Ca(2+)-activated proteolysis. In some cases plasminogen and streptokinase provided acceleration of cultured tissue maturation, improvement of cell adhesion, high survival rate, the increase in quantity and length of processes and their arborisation. Electronic microscopy established the character of structural rearrangements of nervous tissue cells (neurons, astrocytes, oligodendrocytes), reflecting the protective action of plasminogen and streptokinase. In the presence of plasminogen and especially streptokinase, the total number of cultured glioma C6 and neuroblastoma IMR-32 cells, the intracellular contents of protein, RNA and DNA increased several-fold. Addition of plasminogen promoted formation of processes by neuroblastoma cells, this suggests initiation of differentiation of cellular elements. In cultures of sensitive and sympathetic ganglia streptokinase increased proliferation of Schwann cells. These proteins did not cause transformation of PC12 enterochromaffine cells to neurons, though plasminogen facilitated it. Plasminogen addition to cell cultures did not increase fibrinolytic activity of the culture medium in the culture medium, and streptokinase did not lose its plasminogen-activating capacity.

The system of extracellular proteolysing, consists of plasminogen (PGn), its active protease (plasmin), PGn activation and PGn activators inhibitors, influences the nervous tissue functions, their growth, differentiation and proliferation in both, normal and pathological conditions. The purpose of the investigation was to study the effects of exogenous PGn, its activator streptokinase (SK), PK and their equimolar complex on the morpho-functional state neuroblastoma IMR-32 cells. PGn, SK, PK and their complexes stimulated cells proliferation during 1-3 days of incubation, shown by cell quantity increase. We also observed DNA, RNA and protein increase. The low lactate dehydrogenase efflux was evidence of that an addition of the proteins under investigation in the culture medium prevented the development of degenerative alterations connected with serum deprivation. The levels of extracellular PGn-activator activity, as measured by the biochemical fibrinolytic assay, increased over SK. This SK effect vanished on the 3rd day when SK formed complexes with PK. New original facts obtained testify the probability of initiation of neoplastic transformation and tumor growth potentiation.