[3H] dopamine uptake by platelet storage granules in Parkinson's disease.
[3H] Dopamine (DA) uptake by platelet storage granules was determined in 10 never-treated patients with Parkinson's disease (PD) (in 6 of them, also after 6 months of levodopa treatment), in 18 long-term levodopa-treated patients and in 15 age-matched normal controls. Maximum velocity (Vmax) of DA uptake was significantly lower in the group of never-treated PD subjects compared to healthy controls (P < 0.001) and also lower compared to the PD long-term treated patients (P < 0.025). The Vmax of PD never-treated changed after submitting the patients to 6 months treatment (P < 0.025) and became similar to the Vmax in the treated group. The apparent Michaelis constant (Km) of DA uptake in PD never-treated was also significantly different from controls (P < 0.005) and also different (but not significantly) from PD "long-term" treated patients. Decreased DA uptake by platelet storage granules in PD may reflect a generalized defect of dopaminergic cells with an impairment in the vesicularization of DA which may contribute to the symptomatology of this motor disease.
Rabey
J M
JM
Department of Neurology, Sackler Faculty of Medicine, Tel-Aviv University, Israel.
Shabtai
H
H
Graff
E
E
Oberman
Z
Z
D000368:Aged; D000369:Aged, 80 and over; D001792:Blood Platelets / Q000378:metabolism*; D003594:Cytoplasmic Granules / Q000378:metabolism*; D004298:Dopamine / Q000097:blood*; D006801:Humans; D066298:In Vitro Techniques; D007700:Kinetics; D008875:Middle Aged; D010300:Parkinson Disease / Q000097:blood*; D011869:Radioligand Assay; D014316:Tritium
D014316:Tritium; D004298:Dopamine