Summary
The severity of platelet damage induced by hyper- and hypotonic NaCl solutions and
freezing and thawing was assessed by microscopic evaluation and measuring inhibition
of 5-HT uptake. The same techniques were used to quantitate the effects of aggregating
agents. The positively charged macromolecules PS, Poly-L und Poly-O reduced the net
negative surface charge as determined by microelectrophoresis, caused platelet aggregation
and inhibited 5-HT uptake. The damaging effects of Poly-L and Poly-O were more severe
and more closely related to concentration than that of PS. The negatively charged
macromolecules Poly-IC and NaPS increased the anodic electrophoretic mobility. Poly-IC
and heparin caused a low degree of platelet clumping and no inhibition of 5-HT uptake.
NaPS produced severe platelet damage with extensive clumping and complete inhibition
of 5-HT uptake. Na laurate had the same effect, but did not alter electrophoretic
mobility. ADP caused concentration-dependent platelet aggregation and inhibition of
5-HT uptake. The effects of ADP and NaPS were compared in agitated and non-agitated
platelet samples containing identical concentrations of the 2 compounds. Agitation
was found to increase the degree of platelet clumping and to reduce 5-HT uptake.