Malondialdehyde Formation in Rat Platelet-Rich Plasma

G Rajtar; M Livio; J Merino; G de Gaetano

doi:10.1055/s-0038-1650081

Thrombosis and Haemostasis, Inhaltsverzeichnis

Thromb Haemost 1980; 44(02): 049-051
DOI: 10.1055/s-0038-1650081

Original Article

Schattauer GmbH Stuttgart

Malondialdehyde Formation in Rat Platelet-Rich Plasma

I. A Kinetic Approach

Autoren

G Rajtar

¹⁾Visiting Scientist, on leave of absence from the Department of Pharmacology, Medical Academy, University of Lublin, Poland

The Laboratory of Cardiovascular Clinical Pharmacology, Istituto di Ricerche Farmacologiche »Mario Negri«, Milan, Italy
M Livio

²⁾Fellow of the Italian National Research Council (C. N. R.)

The Laboratory of Cardiovascular Clinical Pharmacology, Istituto di Ricerche Farmacologiche »Mario Negri«, Milan, Italy
J Merino

³⁾Visiting Scientist, on leave of absence from the Department of Medicine, Medical School, University of Santander, Spain

The Laboratory of Cardiovascular Clinical Pharmacology, Istituto di Ricerche Farmacologiche »Mario Negri«, Milan, Italy
G de Gaetano

⁴⁾Reprint requests to: Dr. G. de Gaetano, Laboratory of Cardiovascular Clinical Pharmacology, Istituto di Ricerche Farmacologiche, »Mario Negri«, Via Eritrea 62, 20157 Milan, Italy

The Laboratory of Cardiovascular Clinical Pharmacology, Istituto di Ricerche Farmacologiche »Mario Negri«, Milan, Italy

Abstract

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Summary

Malondialdehyde (MDA) is a stable product of arachidonic acid metabolism, catalyzed by the enzyme cyclo-oxygenase. The experimental conditions for measuring the kinetics of MDA formation in rat citrated platelet-rich plasma were defined. Platelets were stimulated with either arachidonic acid, the substrate of MDA, or thrombin, an enzyme which induces release of free arachidonic acid from platelet membrane phospholipids. MDA formation was almost linear for a limited period of time (between 0 and 2 min with arachidonic acid and between 1 and 3 min with thrombin) and was concentration-dependent with saturation kinetics.

The hyperbolic curves obtained could be recast in linear plots (according to Woolf transformation S/V versus S) when arachidonic acid was used. With thrombin, in contrast, the highest concentration at which no MDA production could be detected (3 NIH u/ml) had to be subtracted from each concentration of the enzyme used to obtain Woolf plots. The apparent Km value of arachidonic acid was 0.49 ± 0.09 mM and Vmax was 1.44 ± 0.06 nmoles MDA/1.4 × 10⁹ platelets/min. The corresponding values in experiments with thrombin were 6.5 ± 1.5 NIH u/ml and 0.233 ± 0.012 nmoles MDA/1.4 × 10⁹ platelets/min.

Key words

Blood platelets - Arachidonic acid metabolism - Malondialdehyde - Thrombin - Kinetic analysis

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Referenzen

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