PHYSIOLOGICAL-CHARACTERISTICS OF SEROTONIN TRANSPORTERS ON RAT PLATELETS

Physiological characteristics of serotonin (5-hydroxytryptamine, 5HT) transport through the platelet membrane was investigated in Wistar rat s with our recently developed method permitting repetitive measurement s of transporter kinetics in individual animals. Full kinetic analysis in the population of 91 animals revealed Michaelis constant (K-m) of 0.158 +/- 0.025 mu M and maximal velocity (V-max) of 5HT uptake of 225 +/- 32 pmol per 10(8)platelets min(-1) (mean +/- S.D.). Both kinetic parameters demonstrated normal distribution curves, which for V-max we re slightly skevied toward higher than average values. No gender effec t was shown in frequency distributions, mean values and variability of kinetic parameters. A significant intraindividual correlation between kinetic parameters was found suggesting compensation at the level of the plasma membrane. Kinetic parameters were not influenced by age (un til the middle age) or annual cycle (under laboratory conditions) and were shown to be fairly stable in time, supporting the view that plate let 5HT transport kinetics could be a useful biological trait marker. (C) 1998 Elsevier Science Inc. All rights reserved.