[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.

[Effect of GABA on phosphoinositide cycle and membrane lipid modification in the brain synaptosomes of rats in hypokinesia].

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].

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].

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.

[The effect of estradiol on the initiation of phosphoinositide catabolism in rat brain synaptic membranes].

The in vivo effect of estradiol on phosphoinositide catabolism initiation provoked by K(+)-depolarization of rat brain synaptosomal membranes was studied. The decreased yield of diacylglyceride was revealed on the 5th sec of initiation. It was found that estradiol markedly increases the phospholipid content, particularly that of phosphatidylinositol, in synaptosomal membranes but causes a simultaneous decrease of the neutral lipid content.

[Initiation by estradiol of phosphoinositide catabolism in synaptosome membranes of the rat brain].

A possibility of phosphatidylinositides catabolism initiation was revealed in the rat brain synaptosome membranes during in vitro action of estradiol. It was shown that appreciable enhancement of diacylglycerol yield was observed at already 5th second of initiation, which decreased then until the 30th second and kept the sufficiently high level. The yield of free arachidonic acid had also enhanced.

[An increase of CDP-choline: diglyceride phosphocholine transferase reaction in microsome fraction and its decrease in nuclear membranes of the rat liver after treatment with hydrocortisone].

The availability of CDP-choline: diaglyceride phosphocholine transpherase activity in the rat liver nuclear membrane fraction is shown. It is established that the enzyme activity in nuclear membrane fraction makes up less than 1/3 of the analogous activity in microsomes. The hydrocortisone treatment of animals leads to an increase of the enzyme activity in microsomes and to a decrease in the nuclear membranes.

[Effect of hydrocortisone on the phospholipid composition and activity of various enzymes of phospholipid metabolism in the nuclear membranes of the rat liver].

It was shown that hydrocortisone injections markedly increase the total content of liver nuclear membrane phospholipids, the greatest increase being observed in the phosphatidyl choline level. It was found also that nuclear membranes contain phospholipid metabolism enzymes. The hormone-induced increase in the phospholipid content is accompanied by a marked decrease of the activity of phospholipase A2 (5.

[Role of phospholipids in changes in lysosomal membrane stability in conditions of chronic alcoholic intoxication].

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.