Vitamin K Antagonism of Coumarin Intoxication in the Rat

1986 ◽  
Vol 55 (02) ◽  
pp. 235-239 ◽  
Author(s):  
R Wallin ◽  
D Susan ◽  
D Patrick ◽  
J O Ballard
Keyword(s):  
Vitamin K ◽  
Liver Microsomes ◽  
Clotting Factor ◽  
Vitamin K1 ◽  
Clotting Factors ◽  
Strong Inhibitor ◽  
In Vitro System ◽  
High Concentrations

SummaryAn in vitro system which expresses all enzyme activities related to vitamin K-dependent carboxylation of blood clotting factors was prepared from livers of rats overdosed with warfarin, difenacoum and dicumarol respectively. In this system, the activities of the two pathways that are known to produce active reduced vitamin K1 cofactor for the carboxylation reaction were measured. Also the ability of high concentrations of vitamin Kx to overcome inhibition of clotting factor synthesis was studied. In the systems prepared from livers of warfarin and difenacoum intoxicated rats, pathway I was inactive. Vitamin K epoxide reductase was also inactive which strongly suggests that this enzyme catalyzes the activity of pathway I in vivo. Reduction of vitamin by pathway II bypassed the inactive pathway I and resulted in carboxylation activity. This pathway therefore mediates the antidotic effect of vitamin K1 in the coumarin intoxicated liver. In the in vitro system prepared from dicumarol intoxicated livers the activity of pathway I was not significantly affected. Dicumarol however was a strong inhibitor when added to liver microsomes in vitro.

Vitamin K promotes mineralization, osteoblast-to-osteocyte transition, and an anticatabolic phenotype by γ-carboxylation-dependent and -independent mechanisms

2009 ◽  
Vol 297 (6) ◽  
pp. C1358-C1367 ◽  
Author(s):  
Gerald J. Atkins ◽  
Katie J. Welldon ◽  
Asiri R. Wijenayaka ◽  
Lynda F. Bonewald ◽  
David M. Findlay
Keyword(s):  
Bone Formation ◽  
Vitamin K ◽  
Type I Collagen ◽  
Vitamin K2 ◽  
Type I ◽  
Vitamin K1 ◽  
Vitamin K3 ◽  
Positive Effect

The vitamin K family members phylloquinone (vitamin K1) and the menaquinones (vitamin K2) are under study for their roles in bone metabolism and as potential therapeutic agents for skeletal diseases. We have investigated the effects of two naturally occurring homologs, phytonadione (vitamin K1) and menatetrenone (vitamin K2), and those of the synthetic vitamin K, menadione (vitamin K3), on human primary osteoblasts. All homologs promoted in vitro mineralization by these cells. Vitamin K1-induced mineralization was highly sensitive to warfarin, whereas that induced by vitamins K2 and K3 was less sensitive, implying that γ-carboxylation and other mechanisms, possibly genomic actions through activation of the steroid xenobiotic receptor, are involved in the effect. The positive effect on mineralization was associated with decreased matrix synthesis, evidenced by a decrease from control in expression of type I collagen mRNA, implying a maturational effect. Incubation in the presence of vitamin K2 or K3 in a three-dimensional type I collagen gel culture system resulted in increased numbers of cells with elongated cytoplasmic processes resembling osteocytes. This effect was not warfarin sensitive. Addition of calcein to vitamin K-treated cells revealed vitamin K-dependent deposition of mineral associated with cell processes. These effects are consistent with vitamin K promoting the osteoblast-to-osteocyte transition in humans. To test whether vitamin K may also act on mature osteocytes, we tested the effects of vitamin K on MLO-Y4 cells. Vitamin K reduced receptor activator of NF-κB ligand expression relative to osteoprotegerin by MLO-Y4 cells, an effect also seen in human cultures. Together, our findings suggest that vitamin K promotes the osteoblast-to-osteocyte transition, at the same time decreasing the osteoclastogenic potential of these cells. These may be mechanisms by which vitamin K optimizes bone formation and integrity in vivo and may help explain the net positive effect of vitamin K on bone formation.

scholarly journals The vitamin K-dependent carboxylation system in human osteosarcoma U2-OS cells. Antidotal effect of vitamin K1 and a novel mechanism for the action of warfarin

1990 ◽  
Vol 269 (2) ◽  
pp. 459-464 ◽  
Author(s):  
R Wallin ◽  
F Rossi ◽  
R Loeser ◽  
L L Key
Keyword(s):  
Vitamin K ◽  
Hepg2 Cells ◽  
Clotting Factor ◽  
Osteosarcoma Cell ◽  
Vitamin K1 ◽  
Factor X ◽  
Osteosarcoma Cells ◽  
Human Osteosarcoma ◽  
14C Labelling

An osteoblast-like human osteosarcoma cell line (U2-OS) has been shown to possess a vitamin K-dependent carboxylation system which is similar to the system in human HepG2 cells and in liver and lung from the rat. In an ‘in vitro’ system prepared from these cells, vitamin K1 was shown to overcome warfarin inhibition of gamma-carboxylation carried out by the vitamin K-dependent carboxylase. The data suggest that osteoblasts, the cells involved in synthesis of vitamin K-dependent proteins in bone, can use vitamin K1 as an antidote to warfarin poisoning if enough vitamin K1 can accumulate in the tissue. Five precursors of vitamin K-dependent proteins were identified in osteosarcoma and HepG2 cells respectively. In microsomes (microsomal fractions) from the osteosarcoma cells these precursors revealed apparent molecular masses of 85, 78, 56, 35 and 31 kDa. When osteosarcoma cells were cultured in the presence of warfarin, vitamin K-dependent 14C-labelling of the 78 kDa precursor was enhanced. Selective 14C-labelling of one precursor was also demonstrated in microsomes from HepG2 cells and from rat lung after warfarin treatment. In HepG2 cells this precursor was identified as the precursor of (clotting) Factor X. This unique 14C-labelling pattern of precursors of vitamin K-dependent proteins in microsomes from different cells and tissues reflects a new mechanism underlying the action of warfarin.

scholarly journals Stimulation of the dithiol-dependent reductases in the vitamin K cycle by the thioredoxin system. Strong synergistic effects with protein disulphide-isomerase

1992 ◽  
Vol 281 (1) ◽  
pp. 255-259 ◽  
Author(s):  
B A M Soute ◽  
M M C L Groenen-van Dooren ◽  
A Holmgren ◽  
J Lundström ◽  
C Vermeer
Keyword(s):  
Vitamin K ◽  
Synergistic Effects ◽  
Liver Microsomes ◽  
Bovine Liver ◽  
Secretory Cells ◽  
Protein Disulphide Isomerase ◽  
Vitamin K Cycle ◽  
Thioredoxin System

It has been shown previously that the thioredoxin system (thioredoxin + thioredoxin reductase + NADPH) may replace dithiothreitol (DTT) as a cofactor for vitamin KO and K reductase in salt-washed detergent-solubilized bovine liver microsomes. Here we demonstrate that the system can be improved further by adding protein disulphide-isomerase (PDI) to the components mentioned above. Moreover, NADPH may be replaced by reduced RNAase as a hydrogen donor. In our in vitro system the various protein cofactors were required at concentrations 2-5 orders of magnitude lower than that of DDT, whereas the maximal reaction rate was about 3-fold higher. PDI stimulated the thioredoxin-driven reaction about 10-fold, with an apparent Km value of 8 microM. These data suggest that in the vitro system the formation of disulphide bonds is somehow linked to the vitamin K-dependent carboxylation of glutamate residues. In vivo, both disulphide formation and vitamin K-dependent carboxylation are post-translational modifications taking place at the luminal side of the endoplasmic reticulum of mammalian secretory cells. The possibility that the reactions are also coupled in vivo is discussed.

scholarly journals Warfarin poisoning and vitamin K antagonism in rat and human liver. Design of a system in vitro that mimics the situation in vivo

1987 ◽  
Vol 241 (2) ◽  
pp. 389-396 ◽  
Author(s):  
R Wallin ◽  
L F Martin
Keyword(s):  
Vitamin K ◽  
Human Liver ◽  
Vitamin K1 ◽  
Active Vitamin ◽  
Vitamin K Epoxide Reductase ◽  
Human System ◽  
Epoxide Reductase ◽  
K Function

The present paper describes a system in vitro that has been developed to mimic vitamin K metabolism and vitamin K function in liver. In this system the two pathways that are known to participate in vitamin K reduction are active and the vitamin K-dependent carboxylase accepts a synthetic pentapeptide as substrate. With this system in vitro the effect of warfarin on both pathways was examined under conditions which simulated a warfarin-poisoned liver. Identical experiments were completed with rat and human liver. All activities currently associated with vitamin K metabolism and vitamin K function were similar in the rat and human systems. Warfarin neutralized the ability of pathway I (the vitamin K epoxide reductase pathway) to produce reduced and active vitamin K cofactor for the carboxylase. In both the rat and the human system, however, when warfarin was present, reduced vitamin K cofactor was produced by pathway II (the dehydrogenase pathway). The data are consistent with observations in vivo on the effect of vitamin K1 when used as an antidote. This suggests that the system in vitro reflects the mechanism in vivo by which vitamin K1 overcomes warfarin poisoning.

Deficient synthesis of factor VII by liver tissue of fetal and newborn rats

1960 ◽  
Vol 199 (1) ◽  
pp. 139-142 ◽  
Author(s):  
Gerold M. Grodsky ◽  
Mona Kropatkin ◽  
Judith G. Pool
Keyword(s):  
Vitamin K ◽  
Fetal Liver ◽  
Fetal Tissue ◽  
Factor Vii ◽  
Clotting Factor ◽  
Adult Tissue ◽  
Adult Rats ◽  
Liver Slices

The deficiency of circulating factor VII in the newborn human being was confirmed for the newborn rat and its etiology studied. The ability of liver slices from fetal, newborn and adult rats to synthesize factor VII in vitro was compared under standard conditions. Fetal tissue had about 1/20 and newborn tissue about 1/3 the capacity of adult tissue to form this factor. Although a deficiency of vitamin K has been considered the cause of the clotting factor deficiencies at birth, supplementation of the rat tissue, either with vitamin K added to the liver slices in vitro or vitamin K given to prepartum mother rats in vivo, resulted in only minor improvement of the synthetic rate. Extracts of fetal liver were studied for the presence of an inhibitor of factor VII synthesis and extracts of adult tissue for the presence of a stimulator, but neither could be detected. It was concluded that a functional immaturity of liver enzyme systems involved in synthesis of factor VII exists at birth.

Relationships Between Factor XII-Dependent Systems And The “Prorenin”-Renin System In Human Plasma

1981 ◽  
Author(s):  
E A Wilczynski ◽  
A D Purdon ◽  
D H Osmond
Keyword(s):  
Clotting Factor ◽  
Factor Xii ◽  
Clotting Factors ◽  
In Vitro Techniques ◽  
Subsequent Exposure ◽  
Control Plasma ◽  
Free Plasma

Treatment of plasma with cold (-4°C,72 hr), and with trypsin (0.5 mg trypsin/ml plasma), are well established in-vitro techniques used to activate plasma prorenin. Various clotting factor deficiencies have been found to impair the conversion of prorenin to renin in plasma. Studies with factor XII deficient plasma, in which marked reduction in both cold and tryptic activation was seen, led to further studies on the role of clotting factors and other factor XI I-dependent systems in prorenin activation. Removal of factors II, VII, IX, and X by adsorption onto BaSO4, and subsequent exposure of the residual plasma to cold (-4°C, 48 hr) and trypsin (1 mg/ml), resulted in a decreased capacity for prorenin activation when compared to control plasma, more so in cold than in trypsin-treated plasma. Plasminogen-free plasma responded similarly and, while increased concentrations of trypsin could enhance its prorenin activation to near-normal levels, prolonged cold incubation could not. This suggests that trypsin, added in an appropriate concentration to deficient plasma, may be able to substitute for the missing factor(s), while cold activation is limited by availability of one or more crucial factors. Unmanipulated Fletcher plasma (prekallikrein deficient) has a low level of active renin, and elevated prorenin, symptomatic of a block of prorenin conversion in-vivo. However, cold and tryptic activation were, if anything, relatively greater than normal, especially for trypsin, suggesting that enzymes other than kallikrein are important activators, in-vitro, and can substitute for the missing kallikrein. Thus, neither kallikrein, nor any other single factor studied here, including factor XII, is solely responsible for the activation of plasma prorenin.

scholarly journals The Effect of Vitamin K on Pivka and its Associated Procoagulant Proteins in Liver Disease

1977 ◽  
Author(s):  
R.G. Malia ◽  
F.E. Preston ◽  
E.K. Blackburn
Keyword(s):  
Liver Disease ◽  
Vitamin K ◽  
Intravenous Administration ◽  
Procoagulant Activity ◽  
Clotting Factor ◽  
Vitamin K1 ◽  
Clotting Factors ◽  
Inhibitor Activity ◽  
Normal Individuals ◽  
K Deficiency

Vitamin K deficiency is associated with low procoagulant activity of the vitamin K-dependent clotting factors together with normal concentrations of an immunologically cross-reacting protein associated with the appropriate clotting factor.In this study we have examined the response of the clotting factors II, VII and X together with their appropriate related antigens to the intravenous administration of vitamin K1 in 14 patients with various forms of liver disease. We have also related the observed changes to alterations of the inhibitor activity of PIVKA as detected by the modified thrombotest.A relationship has been established between the rate of appearance of procoagulant activity and the rate of disappearance of PIVKA after the intravenous administration of vitamin K1 in those patients with thrombotest inhibitor activity. In this same group of patients it can also be shown that PIVKA is physico-chemically dissimilar to the related protein of normal individuals.Patients without thrombotest inhibitor activity appear to synthesise decreased amounts of a structurally normal protein which is not influenced by vitamin K.

scholarly journals The Reductive Activity of Human Liver Microsomes for Vitamin K Epoxides

2020 ◽  
Vol 2 (1) ◽  
pp. 7
Author(s):  
Masashi Kawano ◽  
Takuya Araki ◽  
Hideaki Yashima ◽  
Tomonori Nakamura ◽  
Koujirou Yamamoto
Keyword(s):  
Vitamin K ◽  
Human Liver ◽  
Liver Microsomes ◽  
In Vitro Study ◽  
Human Liver Microsomes ◽  
Substrate Affinity ◽  
Clotting Factors ◽  
Blood Coagulation Factors ◽  
Maximum Reaction Rate

Vitamin K (VK) is oxidized to vitamin K epoxide (VK-O) during the production of VK-dependent blood clotting factors. Thereafter, VK-O is reduced to VK by vitamin K epoxide reductase (VKOR) in the liver and reused. This reductive reaction is inhibited by warfarin, an oral anticoagulant. VK in nature is roughly divided into two types, VK1 (phylloquinone) and VK2 (menaquinone). Although their bioavailabilities and elimination half-lives from human blood differ, information on the influence of each VK on the effectiveness of warfarin is limited. In this study, the difference in the metabolism of VK1-O and MK4-O by VKOR was evaluated in an in vitro study using human liver microsomes. The results showed that the substrate affinity (1/Km), and the maximum reaction rate (Vmax) of the VKOR reduction was around 7 and 4 times higher for MK4-O than for VK1-O, respectively. The intrinsic clearance of MK4-O, obtained by dividing the Vmax value by the Km value, was about 30 times greater than that of VK1-O. According to these data, the production of VK-dependent blood coagulation factors can be considered to be dominated mainly by MK4-O, at least under normal conditions. We may thus have to be more careful about controlling the intake of MK4 than VK1 in patients receiving warfarin therapy.Keywords: vitamin K1 (phylloquinone), vitamin K2 (menaquinone), VKOR, warfarin

Effects Of Leucocyte Proteases On Structure And Activity Of Isolated Factor XIII Subunit A AND S

1981 ◽  
Author(s):  
F Holst ◽  
H G Klingemann ◽  
R Egbring ◽  
H Bohn ◽  
K Havemann
Keyword(s):  
Factor Xiii ◽  
Clotting Factors ◽  
Subunit A ◽  
Protein Substrates ◽  
Gradual Loss ◽  
High Concentrations ◽  
Clinical Conditions ◽  
Turn Over

In some diseases (septicemia, leucemia) an activation of clotting by thrombin (eg. DIC) or an unspecific proteolysis of clotting factors by leucocyte proteases can be responsible for coagulopathy.We investigated in vitro the influence of elastase-like protease (ELP) and chymotrypsin-like protease (CLP) on isolated purified factor XIII subunit A and S using the SDS-PAA electrophoresis (Weber and Osborn, 1969). ELP and CLP was purified according to W. Schmidt (1974). Factor XIII was purified by Bohn and Haupt.Results: Using increasing amounts of ELP a correlation between the ELP concentration and the factor XIII split products, which were generated, could be demonstrated. At high concentrations of ELP a complete disappearence of all factor XIII split products could be observed. These digestive effects were shown both on subunit A and on S. The proteolysis of factor XIII was also time dependent. The effects of CLP were not very different from those of ELP. When factor XIII subunit A was digested by ELP, a gradual loss of the ability to crosslink fibrin S occured. As in the literature aj-antitrypsin strongly and aprotinin slightly inhibited the ELP effects on factor XIII.Despite the fact that antiprotease potential in vivo is very high, an accelerated turn over of clotting factors can be expected, when ELP forms complexes with its protein substrates like factor XIII. The decrease of factor XIII in some clinical conditions may be caused by leucocyte proteases.

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