[pH gradient in the membranes of serotonin-containing granules of thrombocytes: principles for studying them using fluorescent amino-derivatives of acridine].

A new method has been devised for determination of gradient pH and buffering capacity in 5-HT-containing granules of platelets. It is based on the ability of 5-HT granules to accumulate acridine derivatives so that the ratio of the label concentrations outside and inside is equal to the proton concentration ratio. Simultaneous recording of the fluorescence intensity and light transmission of the platelet-rich plasma has been made use of in comparing the kinetics of the intragranular pH collapse and platelet aggregation.