Thromb Haemost 1989; 62(02): 733-741
DOI: 10.1055/s-0038-1646893
Original Article
Schattauer GmbH Stuttgart

Platelet Size Affects both Micro- and Macro-Aggregation: Contributions of Platelet Number, Volume Fraction and Cell Surface

Truman Wong
The Department of Physiology, McGill University, Montreal, Canada
,
Lloyd Pedvis
The Department of Physiology, McGill University, Montreal, Canada
,
Mony Frojmovic
The Department of Physiology, McGill University, Montreal, Canada
› Author Affiliations
Further Information

Publication History

Received 30 December 1988

Accepted after revision 27 April 1989

Publication Date:
30 June 2018 (online)

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Summary

The relationship between platelet size (v), platelet number (N0), platelet volume fraction (φ) and platelet aggregation was evaluated in human platelet subpopulations separated on the basis of volume using counterflow centrifugation. The original platelet population and three size-dependent platelet fractions were concentrated and resuspended in autologous citrated platelet-poor plasma at varying N0. Micro-aggregation (PA) and macro-aggregation (TA) were determined respectively by electronic particle counting and light transmission (turbidometry). At similar N0, large platelets were about two-fold more sensitive and more rapidly recruited into both micro (PA) and macro (TA) aggregates in response to ADP than the small platelets (v were respectively 7.3 ± 0.2 and 4.2 ± 0.2 fl, each 16 ± 4% of the total population). At volume fractions favouring the small platelets, however, the above differences persisted for PA, but not for TA. Similar size-dependent differences were observed for two other receptor-mediated platelet activators, namely a stable thromboxane A2 analogue (U46619) and platelet activating factor (PAF), but not for ristocetin-induced agglutination. Increasing platelet size appears to optimize platelet aggregation due to (i) the simple geometric advantage of large-sized platelets associated with any given N0, seen for both PA und TA, and (ii) intrinsic differences in size-dependent subpopulations which favour more efficient platelet membrane surface changes associated with receptor-mediated micro-aggregation (PA), for which a likely model is proposed.