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Biomedical subjects

I Mucha

Publications and source records attributed to I Mucha.

46 records · Page 3Linked to original sources
PubMed1988

cAMP dependent inhibition of thromboxane A2, prostacyclin and PGF2 alpha synthesis in mouse hepatocytes.

The role of cAMP dependent regulation in thromboxane A2, prostacyclin and PGF2 alpha synthesis (measured by radioimmunoassay) was investigated in isolated mouse hepatocytes and in microsomal membranes prepared from these cells. In isolated hepatocytes N6,O2-dibutyryl cAMP inhibited the formation of all the three derivatives, while calcium ionophore A 23187 stimulated their synthesis. Addition of the dissociated catalytic subunit of cAMP dependent protein kinase and ATP to microsomal membranes inhibited the production of TXA2, PGI2 and PGF2 alpha by about 50% and this inhibition was counteracted by the combined addition of heat stable inhibitor protein of cAMP dependent protein kinase. It is concluded that in parenchymal liver cells cAMP dependent phosphorylation is directly involved in the inhibition of prostanoid synthesis.

Animals↗
PubMed1987

Prostanoid synthesis in isolated parenchymal and nonparenchymal mouse liver cells in the presence of arachidonic acid.

Prostanoid synthesis was investigated in suspensions of isolated mouse hepatocytes and nonparenchymal liver cells. A stable metabolite of thromboxane A2 (TXB2) of prostacyclin (6-keto PGF1 alpha) and one of the prostaglandins (PGF2 alpha) was detected by radio-immuno-assay (RIA). Hepatocytes synthesized mainly TXB2, while smaller amounts of 6-keto PGF1 alpha and PGF2 alpha were detected during 60 min incubation. Homogenization of hepatocytes caused a slight increase of TXB2 production and provoked the synthesis of PGF2 alpha and 6-keto PGF1 alpha. The addition of arachidonate to hepatocytes did not influence prostanoid production at concentrations below 10-5M. Higher concentrations further increased TXB2 production and also increased the synthesis of 6-keto PGF1 alpha and PGF2 alpha. Nonparenchymal cells synthesized all the three types of prostanoids and homogenization of these cells did not result in a marked change. The addition of 10(-7)-10(-5)M arachidonate increased the TXB2, 6-keto PGF1 alpha and PGF2 alpha synthesis in nonparenchymal cells. No further increase was found at higher concentrations.

Animals↗
PubMed1987

Inhibitory effect of A 23187 on protein synthesis in isolated murine hepatocytes.

The effect of the Ca ionophore A 23187 on amino acid incorporation into protein, on gluconeogenesis and on synthesis of some eicosanoids was investigated in isolated mouse hepatocytes (i) in the presence of 2.5 mM Ca2+, (ii) in the absence of Ca2+ and in the presence of 0.2 mM EGTA, (iii) after calcium depletion. A 23187 inhibited amino acid incorporation into protein both in the presence and in the absence of Ca2+ in a concentration dependent manner, whereas in the absence of Ca2+ the known stimulating effects of A 23187 on eicosanoid synthesis could not be detected. In hepatocytes prepared from 24 h starved mice A 23187 increased the rate of gluconeogenesis and similarly to eicosanoid synthesis this stimulation in the absence of Ca2+ could not be observed. On the other hand, after calcium depletion the inhibition of protein synthesis by A 23187 was markedly moderated. It is concluded that the effect of A 23187 on protein synthesis is also related to its ionophoretic effect but calcium sensitivity in this effect is smaller than in gluconeogenesis or eicosanoid synthesis.

Animals↗
PubMed1984

Uptake of arachidonic acid, arachidic acid, oleic acid and their incorporation into phospholipids and triacylglycerols of isolated murine hepatocytes. Effect of thrombin-antithrombin III complex.

Uptake and metabolism of arachidonic acid, arachidic acid and oleic acid were investigated in isolated hepatocytes prepared from mouse liver with the collagenase perfusion method. The rate of uptake of arachidonic acid was time- and concentration- dependent. 94-98% of the arachidonic acid was incorporated into the phospholipid and triacylglycerol fractions following a 60 min incubation period at 37 degrees C. In the presence of thrombin-anti-thrombin III complex a change in the distribution of arachidonic acid incorporated into lipid fractions was found, i.e. increased incorporation into phosphatidyl-serine and phosphatidylethanolamine, whereas the uptake was not altered. There was no change in the uptake and incorporation of arachidic acid and oleic acid.

Animals↗
PubMed1984

Prostaglandin and thromboxane synthesizing activity in isolated murine hepatocytes and nonparenchymal liver cells.

Prostanoid synthesis from 3H-arachidonic acid was compared in isolated parenchymal and nonparenchymal murine liver cells. The cells incorporated arachidonic acid into phospholipids but no prostanoid synthesis could be measured during 30 min incubation. Conditions necessary for prostanoid synthesis were different in parenchymal and nonparenchymal cells and the products were also different. Prostanoid synthesis could be induced by in vitro partial hepatectomy: parenchymal cells synthesized thromboxane A2 whereas nonparenchymal cells produced prostaglandin E2 and F2 alpha. Prostaglandin E2 and F2 alpha synthesis could be provoked also by homogenization of the nonparenchymal cells prepared from normal liver, while the homogenates of parenchymal cells prepared from normal liver did not synthesize thromboxane. Imidazole and indomethacin inhibited the production of thromboxane and prostaglandins, respectively. Our results suggest that the various cell types of the liver respond by the synthesis of different and specific prostanoids after the same injury.

Animals↗
PubMed1983

Arachidonic acid metabolism in reproductive tissues of pregnant guinea pig under in vivo circumstances.

Uptake and metabolism of tritium labelled arachidonic acid have been studied under in vivo circumstances in placenta, uterus and fetal membranes of pregnant guinea pigs on days 40 and 60 of pregnancy. Distribution of radioactivity within the lipid fractions of the selected tissues showed a characteristic pattern depending on the gestational ages. Composition of labelled lipids was determined by radio thin layer chromatography and quantitated with liquid scintillation measurements. The main site of arachidonic acid incorporation was the 2-position of phosphatidylcholine. Near term, a considerable PGF2 alpha-synthesis from exogenously administered 3-H-arachidonic acid could be demonstrated for the first time "in vivo".

Animals↗
PubMedDate not supplied

Effects of bisphosphonates on prostaglandin E2 and thromboxane B2 production in human whole blood and monocytes stimulated by lipopolysaccharide and A23187.

Bisphosphonates are antiatherosclerotic, suppress monocyte-macrophages, and modulate proinflammatory mediators. Prostaglandin (PG) E(2), thromboxane (TX) A(2), and cyclooxygenase-2 (COX-2) enzyme are involved in inflammation and atherosclerosis. We studied the effects of four bisphosphonates (etidronate, clodronate, tiludronate, and alendronate) on PGE(2) and TXB(2) production in human whole blood and monocytes. PGE(2) and TXB(2) were determined by direct radioimmunoassay and COX-2 expression by Western blot. In whole blood, the bisphosphonates did not modulate the increase in PGE(2) and TXB(2) concentrations induced by calcium ionophore A23187 or lipopolysaccharide (LPS). None of the bisphosphonates did change PGE(2) and TXB(2) concentration after spontaneous clotting. A23187- and spontaneous clotting-induced PGE(2) and TXB(2) productions were inhibited over 90% by acetylsalicylic acid (ASA), and LPS-induced PGE(2) and TXB(2) formations were inhibited over 90% by nimesulide. None of the bisphosphonates altered these inhibitions. In monocytes, etidronate and clodronate augmented A23187-stimulated PGE(2) production 2.5- to 3.2-fold (p < 0.05). LPS- or A2318-induced elevations in TXB(2) were not influenced by the bisphosphonates. The tested bisphosphonates neither induced COX-2 expression nor modulated LPS-induced COX-2 expression in monocytes. The results suggest that the antiatherosclerotic effects of bisphosphonates are not mediated via PGE(2), TXA(2), or COX-2, and the bisphosphonates do not interfere with the suppression of platelet COX-1 activity by ASA and COX-2 activity by nimesulide.

Aspirin↗