[Regularities of endogenous lipid metabolites formation in phorbol 12-miristate 13-acetate-stimulated peripheral blood lymphocytes at leukemia].

Regularities of biologically active lipid metabolites formation in dynamics (5, 10, 30, 60 s) by phorbol 12-miristate 13-acetate stimulation in [14C]palmitic acid have been investigated in normal and leukemia peripheral blood lymphocytes prelabeled with [14C]palmitate. In normal cells there was two-phase formation of 1,2-diacylglycerol (5, 30 s), lysophosphatidylcholine (10, 60 s), as well as free palmitic acid at 10 s of stimulation. Under the identical experimental conditions there was inhibition of investigated lipid release processes at early (5 and 10 s) stages of stimulation of leukemic lymphocytes. At later (30, 60 s) terms of these lymphocytes the activation, basically, similar to norm changes in the formation of palmitic acid-containing metabolites except free palmitic acid (the level of which raised only at 60 second of the post-stimulation) was found. Various protein kinases C are involved in the regulation of investigated lipid levels at certain stages of signal transduction both in norm, and in blast cells. Short-term (5, 10 s) activations of healthy donors lymphocytes are coupled to functioning of Ca2+-independent isoforms of protein kinase C. The inhibition of this protein kinase C in leukemic cells leads to normalization of the investigated lipid release. The data obtained suggests disorders of early membrane-bound reactions in agonist - and a protein kinase C-mediated processes of formation palmitic acid-containing lipid metabolites in the leukemic cells in comparison with the norm.

[Effect of GABA on phosphoinositide cycle and membrane lipid modification in the brain synaptosomes of rats in hypokinesia]. / Vliianie GAMK na fosfoinozitidnyi tsikl i modifikatsii membrannykh lipidov sinaptosom mozga krys v usloviiakh gipokinezii.

The influence of a 30-day hypokinesia on the phosphoinositide cycle (PIC) initiation and on the inclusion of [14C]-arachidonic acid into cerebral synaptosome phospholipids was studied in rats. The results show that the catabolism of phospholipids prevails on the background of signal transduction in synaptosomes on the 30th day of hypokinesia. The effect of gamma-aminobutyric acid (GABA) is manifested by a sharp increase in the PIC activity 5 sec upon initiation and leads to normalization of the PIC activity in the late stage (5 min).

[Catabolism of membrane phosphatidylcholines during early stages of mitogenic initiation of phosphoinositide cycle in lymphocytes]. / Katabolizm membrannykh fosfatidilkholinov v rannie sroki mitogennoi initsiatsii fosfoinozitidnogo tsikla v limfotsitakh.

Deacylation of the phosphatidylcholine fraction in plasma membranes of rat thymocytes and human blood lymphocytes was studied as well as its relationship to the activation of phosphoinositide-specific phosphodiesterase at early stages of mitogen-initiated phosphoinositide cycle. The data indicate that in lymphocyte membranes, enzymatic system of cascade deacylation of the phosphatidylcholine fraction includes calcium-activated phospholipase A1 and lysophospholipase. The enzyme system contributes to the rapid and reversible modification of the lipid bilayer of lymphocyte plasma membrane and can cooperate with phosphoinositide-specific phosphodiesterase during its activation at early stages of the initiation of phosphoinositide pathway during translocation of the external mitogenic signal.

[The enzymatic system of phospholipid deacylation-reacylation in rat liver lysosomal membranes]. / Fermentnaia sistema deatsilirovaniia-reatsilirovaniia fosfolipidov v membranakh lizosom pecheni krys.

It has been shown for the first time that lysosomal (tritosomal) membranes of rat liver contain enzymes that are responsible for the deacylation-reacylation of phospholipids; their activity optimum lies at pH 7.0. Deacylation of lysosomal membrane phospholipids is controlled by a cascade of enzymatic reactions involving Ca2(+)-dependent phospholipase A1 which exhibits the maximal activity at 2.5 mM Ca2+ and at neutral values of pH, as well as lysophospholipase. Reacylation of lyso-derivatives of phospholipids is catalyzed by Mg2(+)-activated oleoyl-CoA:lysophosphatidylcholine acyltransferase having an activity optimum at pH 7.2.

[Role of phospholipids in changes in lysosomal membrane stability in conditions of chronic alcoholic intoxication]. / Rol' fosfolipidov v izmenenii stabil'nosti lizosomal'nykh membran v usloviiakh khronicheskoi alkogol'noi intoksikatsii.

Pronounced destabilization of liver lysosomal membranes has been revealed in rats in conditions of 30-day-long alcohol intoxication. Noticeable fractional changes in phospholipid composition of lysosomal membranes have been found. Significant increase in lysophosphatidylethanolamine and lysophosphatidylcholine levels have been observed. Type A2 phospholipase activity was found in lysosomal fractions, with the enzyme activity Ca2+-dependent, optimal at pH 8 and increasing many-fold following alcohol intoxication. The changes in lysosomal membrane phospholipids appear to be related to phospholipase A2 activation.