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Biotechnology and Applied Biochemistry (2001) 34, (19–23) (Printed in Great Britain)

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Impaired L-arginine uptake in platelets from type-2 diabetic patients

Maria Grazia Signorello*, Marco Giovine*, Raffaele Pascale*, Luigi Cataldi†, Caterina Bordone†, Umberto Benatti* and Giuliana Leoncini*¹

*Department of Experimental Medicine, Biochemistry Section, University of Genoa, Viale Benedetto XV 1, 16132 Genova, Italy, and †Diabetes Unit, San Martino Hospital, Largo R. Benzi 10, 16132 Genoa, Italy

Key words: A23187, collagen, stimulation, thrombin, type-2 diabetes.

¹To whom correspondence should be addressed (e-mail leoncini@unige.it).

The L-arginine uptake of resting platelets from type-2 diabetic patients and control subjects was measured and the kinetic parameters defined. The effect of platelet stimulation with agonists was also investigated. Kinetic studies showed that the K_m value for L-arginine transport was not different in patients compared with control subjects, while V_max was significantly decreased in patients compared with controls. Moreover, agonists able to mobilize Ca²⁺ produced a further decrease in the L-arginine uptake in controls and in patients, suggesting that Ca²⁺ intracellular levels down-regulate L-arginine transport in platelets from both control subjects and patients. Data suggest that drugs designed to control intracellular Ca²⁺ might restore platelet function in diabetic patients.

Received 5 April 2001/13 April 2001; accepted 27 April 2001

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