Stability of prostaglandin I2 in human blood

Pifer, D. David; Cagen, Lauren M.; Chesney, Carolyn M.

doi:10.1016/0090-6980(81)90135-0

Cited by 55 publications

(15 citation statements)

References 22 publications

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“…Both heparin and heparinoid did not alter the rate of decay of PGI2 in PPP or fatty acid free human albumin solutions in vitro. PGI2 is stabilised by plasma and the plasma protein responsible for this effect is albumin (Mikhailidis et al, 1981;1982a, b;Orchard & Robinson, 1981;Pifer et al, 1981;Wynalda & Fitzpatrick, 1980). Our experiments demonstrating the absence of a heparin or heparinoid effect on PGI2 decay in vitro suggest that neither of these compounds directly interfere with the PGI2-albumin interaction.…”

Section: Discussionmentioning

confidence: 75%

Comparison of the effect of a conventional heparin and a low molecular weight heparinoid on platelet function.

Mikhailidis¹,

Barradas²,

Mikhailidis³

et al. 1984

Brit J Clinical Pharma

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In a study comparing the in vitro effects of heparin and a low molecular weight heparinoid (Organon 10172) on aggregation of platelets from normal subjects, we have demonstrated that whereas heparin markedly enhances platelet aggregation induced by other aggregators and inhibits the anti‐aggregatory effect of epoprostenol (prostacyclin, PGI2), heparinoid does not produce such effects. The use of heparinoid may thus have a significant advantage over that of heparin in situations where enhanced platelet aggregation is the main factor leading to thrombosis or where heparin treatment is followed by thrombocytopaenia.

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Section: Discussionmentioning

confidence: 75%

Comparison of the effect of a conventional heparin and a low molecular weight heparinoid on platelet function.

Mikhailidis¹,

Barradas²,

Mikhailidis³

et al. 1984

Brit J Clinical Pharma

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“…The concentration of PGI2 was high in order to maintain inhibition throughout the experiment. The half-life of PGI2 is about 20 min in plasma or buffer containing albumin, pH 7.5 (22). Platelets obtained in this manner showed normal aggregation with collagen in 1-2 hr.…”

Section: Resultsmentioning

confidence: 89%

Subcellular localization and secretion of factor V from human platelets.

Chesney¹,

Pifer²,

Colman³

1981

Proc. Natl. Acad. Sci. U.S.A.

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ABSTRACT' Factor V, a plasma protein cofactor necessary for optimal conversion of prothrombin to thrombin, is also present in considerable concentration in blood platelets (9.9 units per 109 platelets). Subcellular fractionation by. two methods has localized factor V in the a granules of-unstimulated platelets. ADP and epinephrine cause release of4.6% and 6.4%, respectively, ofthe total factor V, a process completely inhibited by cyclooxygenase alkylation by aspirin. In contrast, collagen causes release of 25% of platelet factor V, a process only partially suppressed by aspirin. Secretion of factor V depends on the availability of metabolic energy, because antimycin A,. an inhibitor of aerobic metabolism, and 2-deoxyglucose, an inhibitor of anaerobic glycolysis, together almost totally inhibited the secretion of factor V induced by collagen. The data establish that factor V is not normally available on unstimulated platelets but can be secreted from a granules upon stimulation with physiological agents such as ADP, epinephrine, and collagen. Because factor V is known to serve as a receptor for factor Xa, the exposure of factor V on platelets consequent to release would accelerate the process of blood coagulation.One year after the discovery of factor V in plasma, Ware et al.(1) recognized that platelets also contain an accelerator of prothrombin conversion. Though this coagulant activity was more stable to heat inactivation and storage than was plasma factor V, it was generally assumed to be the plasma factor adsorbed to the platelet surface (2, 3). In 1975, Breederveld et aL (4), using gel filtration to isolate platelets from plasma, found minimal activity of factor V associated with platelets but were able to increase the V activity by freeze-thawing. 0sterud et aL (5) confirmed this observation and showed that platelets contain an activated form offactor V as well as a platelet activator ofplasma factor V. Kane et aL (6) have presented convincing evidence that factor Xa binds to the platelet membrane at a binding site that is identical to or requires the presence of factor V.Despite these important observations, several questions remain in evaluating the influence of platelet factor V on the hemostatic and possible thrombotic processes. What is the sub, cellular localization offactor V? Are prostaglandin synthesis and metabolic energy required for its release? Do collagen, ADP, and epinephrine release factor V as thrombin does? This study attempts to answer these questions. MATERIALS AND METHODSBovine serum albumin (fraction V), ADP, epinephrine, and bovine fibrinogen (fraction 1, type IV, 93% clottable) were supplied by Sigma. Human fibrinogen (grade L, 95%

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“…This the addition of HDL, the half-life was prolonged from 4.8 min (o) to 22.3 min (.). Albumin has been reported to bind PGI2 and to prolong PGI2 activity (3)(4)(5)(6)(7). Indeed, the PSF activity was found in human albumin (Cohn fraction V albumin, Sigma).…”

Section: Resultsmentioning

confidence: 99%