Uptake and efflux of 14-C-dopamine in platelets: evidence for a generalized defect in Parkinson's disease.
Thirty-five parkinsonian patients (five untreated, six with levodopa only, seven with levodopa plus Ro 4-4602, nine with anticholinergic and/or antihistaminic medication, and eight with the anticholinergic/antihistaminic medication plus amantadine) and 35 age-matched control subjects were studied. Platelets isolated from each individual plasma were incubated with 14C-dopamine. Uptake was found to be decreased to a significant degree in all treated or untreated parkinsonian patients when compared with control subjects. Anticholinergic and/or antihistaminic medication, with or without amantadine, further decreased the dopamine uptake into platelets, while levodopa alone or with Ro 4-4602 returned uptake values to near normal. Dopamine efflux paralleled exactly the uptake values. The fact that parkinsonian platelets exhibit impaired dopamine uptake, while age-matched control platelets do not, constitutes the first direct evidence in favor of a generalized dopamine defect in Parkinson's disease.
D000328:Adult; D000368:Aged; D000547:Amantadine / Q000494:pharmacology; D065105:Aromatic Amino Acid Decarboxylase Inhibitors; D001545:Benserazide / Q000627:therapeutic use; D001792:Blood Platelets / Q000378:metabolism*; D002250:Carbon Radioisotopes; D003864:Depression, Chemical; D004298:Dopamine / Q000378:metabolism*; D004357:Drug Synergism; D004359:Drug Therapy, Combination; D004791:Enzyme Inhibitors / Q000008:administration & dosage / Q000627:therapeutic use; D005260:Female; D006634:Histamine H1 Antagonists / Q000627:therapeutic use; D006801:Humans; D007980:Levodopa / Q000008:administration & dosage / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged; D010276:Parasympatholytics / Q000627:therapeutic use; D010300:Parkinson Disease / Q000188:drug therapy / Q000378:metabolism*; D013997:Time Factors; D014282:Trihexyphenidyl / Q000494:pharmacology
D065105:Aromatic Amino Acid Decarboxylase Inhibitors; D002250:Carbon Radioisotopes; D004791:Enzyme Inhibitors; D006634:Histamine H1 Antagonists; D010276:Parasympatholytics; D007980:Levodopa; D014282:Trihexyphenidyl; D001545:Benserazide; D000547:Amantadine; D004298:Dopamine