[pH changes in the matrix of serotonin organelles of stimulated thrombocytes]

The changes of pH gradient on serotonin organelle membranes can be observed using the fluorescent marker acridine orange. This gradient decreases with thrombin activation of the blood plates. The fall of delta pH can be induced by ammonium salts which also influence the ADP-induced cellular aggregation. NH4 ions added simultaneously with low doses of ADP potentiate cellular aggregation, and added after ADP-induced interaction of cells lead to another wave of intercellular contacts inhibited by mepacrin. Fluorescent acridin aminoderivatives can be used both for kinetic observations of delta pH on the serotonin organelle membranes of native platelets and for studying the interaction of the systems responsible for maintaining this gradient with the systems of prostaglandin and adenine nucleotide metabolism.