engleski

Platelet serotonin transporter (5HTt) : physiological influences on kinetic characteristics in a large human population

The present study had two goals: first, to give detailed description of the reliable method for full kinetic analysis of serotonin transporter (5HTt) on the membrane of human platelets, and second, as a main issue, to report on fundamental physiological characteristics of this transmembrane transport on a large population of healthy individuals. Full-kinetics analysis of platelet serotonin uptake were performed on 334 blood donors of both sexes by the use of 14C-radioisotopic method, which was first optimized according assumptions of enzyme kinetic analyses, with regard to platelet concentration, duration of uptake, concentration of substrate as well as important technical parameters (underpressure of filtration, blanks, incubating temperature etc). Kinetic parameters of platelet serotonin uptake in the whole population were for Vmax: 142  25.3 pmol 5HT/108 platelets/minute and for Km: 0.404  0.089 M 5HT. Besides report on kinetic values of 5HT transporter protein, we have also described fundamental physiological characteristics of Vmax, Km and their derivative, Vmax/Km (transporter efficiency): range and frequency distribution of normal values, intraindividual stability over time, lack of age influence, gender dependence and seasonal variations. The report on kinetic values and main physiological characteristics of serotonin transport into platelets, obtained by the use of thoroughly reassessed methodology, and on by far the largest human population studied until now, offers a reliable frame of reference for pathophysiological studies of this parameter in various clinical fields.

serotonin transporter; 5-HTt; SERT; blood platelets; physiology; kinetic analysis

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