The increase of the openings of the surface-connected canalicular system in weakly stimulated platelets is prevented by a carbochromen derivative. A computerized morphometric analysis of freeze-etched human platelet plasma-membrane

Abstract

When thrombin is added to platelet rich plasma at very low concentrations (0.02 U/ml), platelets undergo an activation process. Under these conditions platelets discharge beta-throm-boglobulin, platelet factor 4 and the “platelet derived growth factor”. In this paper we present evidence that when human platelets are weakly stimulated with thrombin, the number of openings of the surface connected canalicular system (SCCS) increases. This was observed ultrastructurally by the freeze-etching technique. 8-chlorocarbochromen, an antiaggregating drug, seems to inhibit this increase.