ALTERED PLASMA-LEVEL AND UPTAKE OF DOPAMINE BY PLATELETS IN SOME HUMAN-MALIGNANT TUMORS

Besides cardiovascular and renal functions, the influence of dopamine (DA) in immune functions has been reported by several authors. Since i mmune functions has considerable influence on malignant growth, it is therefore essential to know the status of plasma dopamine in cancer pa tients. In the present study, the plasma dopamine level was evaluated and compared with age and sex matched normal controls. Since human pla telets actively uptake plasma dopamine, the uptake of H-3-DA by platel ets from cancer patients was also evaluated. Results demonstrate that irrespective of the site and histological type of malignant neoplasms, concomitant with increased plasma dopamine level, the uptake of H-3-D A by platelets decreased significantly than controls. Acute sympatheti c tone is suggested for increased plasma dopamine level in cancer pati ents. Human platelets which takes up and release dopamine, has been su ggested by several authors as a peripheral model to study dopaminergic neurons in the brain. Therefore, this decreased uptake of H-3-DA by p latelets from cancer patients is of significance as the incidence of c ancer is more prevalent in patients suffering from Parkinson's disease where an irreversable damage to the central dopaminergic neurons has been suggested.