The Incorporation of Radioactive Phosphorus Into the Phospholipids of Human Leukemic Leukocytes and Platelets*

Firkin, Barry G.; Williams, William J.

doi:10.1172/jci104270

Cited by 36 publications

(14 citation statements)

References 37 publications

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“…These studies extend those previously reported in which it was found that 'POL is incorporated rapidly into phosphatidic acid and phosphoinositide in platelets in vitro (1). (52) have reported that platelets can synthesize phospholipids de novo from labeled a-glycerophosphate.…”

Section: Discussionsupporting

confidence: 90%

“…Previous studies have shown that human platelets incorporate radioactive phosphate into phospholipids both in vivo and in vitro (1)(2)(3)(4)(5). In the in vitro studies, phosphatidic acid and phosphatidylinositol were labeled more rapidly than other phosphatides, suggesting that these compounds were synthesized rapidly and that they might be responsible for some important metabolic function.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Biosynthesis of cytidine diphosphate diglyceride by human platelets

Call¹,

Williams²

1970

J. Clin. Invest.

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Section: Discussionsupporting

confidence: 90%

Section: Introductionmentioning

confidence: 99%

Biosynthesis of cytidine diphosphate diglyceride by human platelets

Call¹,

Williams²

1970

J. Clin. Invest.

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“…In this e)-periment, the radioactivity in PS remained constant after the first 30 min and did not decrease significantly (3). Previous studies using 'P incorporation suggested that circulating platelets might synthesize phospholipid as well (6). In these studies, Firkin and Williams suggested that phosphatidic acid and phosphatidyl inositol were metabolically the most rapidly turning over lipids in platelets, although they were unable to determine whether net synthesis occurred.…”

Section: Methodsmentioning

confidence: 96%

Lipid metabolism in human platelets

Lewis¹,

Majerus²

1969

J. Clin. Invest.

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A B S T R A C T Washed human platelets were incubated with radioactive glycerol; the platelets were able to synthesize de novo the major phosphoglycerides including phosphatidic acid, phosphatidylinositol, phosphatidyl choline, phosphatidyl ethanolamine, and phosphatidyl serine. The specific activities of the phosphoglycerides obtained after glycerol incorporation indicate that phosphatidic acid, phosphatidylinositol, and phosphatidyl choline are metabolically active relative to phosphatidyl ethanolamine and that formation of phosphatidyl serine occurs to a much more limited extent. When platelets were incubated with bovine thrombin, 1 U/ml, the pattern of glycerol incorporation into phospholipid was changed. There was a 3-fold decrease in the total incorporation into lipid in 30 min with a relative 5-fold decreased incorporation into phosphatidyl choline and phosphatidyl ethanolamine and a 5-fold increased incorporation into phosphatidyl serine. The increased incorporation into phosphatidyl serine was maximal within the first 2 min but was transient, since within 20 minutes, the rate returned to that seen in platelets incubated with glycerol alone. Purified human thrombin also produced this same effect on phospholipid synthesis in platelets. Trypsin produced effects on phosphoglyceride formation similar to those seen with thrombin, and the trypsin-induced effect was inhibited by prior imcubation of trypsin with soybean trypsin inhibitor, suggesting that proteolysis may be required for the observed effects on phospholipid synthesis.

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“…Later, it became apparent that in various other tissues, liver (5,6), erythrocytes (7,8), leukocytes (9)(10)(11), and kidney (5,12), the in vitro incorporation of 'Pt was at a very high rate in the inositides.…”

Section: Introductionmentioning

confidence: 99%

Quantification of human platelet inositides and the influence of ionic environment on their incorporation of orthophosphate-32P

Cohen¹,

Broekman²,

Verkley³

et al. 1971

J. Clin. Invest.

112

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A B S T R A C T Platelets are a rich source for the study of inositol lipids in man. The substitution of an EDTAKCl solution for the water component of the Bligh and Dyer procedure permitted quantitative extraction of polyphosphoinositides. The latter, with monophosphoinositide, were found to comprise, on a molar basis, 6.7% of total platelet phospholipids. Study of the incorporation of orthophosphate-'P into platelet phospholipids was further simplified by separating eight 'P-labeled lipids, including the inositides, with a single chromatographic development on formaldehyde-treated paper. Particular attention was paid to the influence of ionic environment on the pattern and degree of labeling.In 300 mOsm media major phospholipids other than the inositides were not labeled. Small amounts of label appeared in certain trace phospholipids, notably phosphatidic acid. In 150 mOsm media, labeling of inositides was moderately increased, that of trace phospholipids enormously so. The increased labeling was not solely due to thrombocytolysis since (a) platelet disruption by sonication or freeze-thawing abolished 'P incorporation into phospholipids and (b) in timed studies, restoration of osmolarity to 300 mOsm by addition of hypertonic sorbitol blunted the enhancement effect of previous 150 mOsm exposure. Lowering K and compensatorily increasing Na concentration of 300 mOsm media also stimulated aP labeling of inositides and, to a lesser extent, the trace phospholipids. However, the pattern and degree of stimulation were not as strikingly altered as in the osmolarity studies.

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The Incorporation of Radioactive Phosphorus Into the Phospholipids of Human Leukemic Leukocytes and Platelets*

Cited by 36 publications

References 37 publications

Biosynthesis of cytidine diphosphate diglyceride by human platelets

Biosynthesis of cytidine diphosphate diglyceride by human platelets

Lipid metabolism in human platelets

Quantification of human platelet inositides and the influence of ionic environment on their incorporation of orthophosphate-32P

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