5-Hydroxytryptamine (5-HT) transport in Down's syndrome blood platelets: Effect of K super(+) loading

It has been postulated that blood platelets may act as an accessible model for certain aspects of amine metabolism in the CNS, particularly for the transport and storage of 5-hydroxytryptamine (5-HT). Blood platelets from subjects with Down's Syndrome (D.S.) exhibit decreased accumulation and storage of 5-HT. In addition, D.S. platelets have an increased content of Na super(+) and a decreased content of K super(+) suggesting that decreased 5-HT transport could be secondary to disturbances in the transmembrane ion gradients. The present experiments were designed to test the hypothesis that low intracellular K super(+) contributes to the decreased uptake of 5-HT in D.S. platelets.