Guanine nucleotide binding proteins in opioid-dependent patients

Guanine nucleotide binding (G) protein levels and functioning in the platelets of 19 methadone-maintained patients were compared to age and sex matched, normal controls. We found that in the methadone patients, Gas-levels were significantly higher, while the levels of Gαi 1/2 and pertussis toxin catalyzed [32P]ADP ribosylation were significantly lower compared to control subjects in platelet membranes. We have further found that when all three of these biochemical indicators were combined in a discriminant function analysis, 79% of the methadone patients were correctly classified and 83% of the controls were correctly classified.