Relationship between internal Na+/K+ and the accumulation of 14C‐5‐hydroxytryptamine by rat platelets

Abstract

Summary: 5‐Hydroxytryptamine (5‐HT) transport has been investigated in rat blood platelets poisoned with dinitrophenol‐sodium fluoride or ouabain. The inhibition of transport produced by different concentrations of the metabolic inhibitors has been correlated with changes in the internal Na⁺ and K⁺ concentrations of the platelets. Platelets poisoned in a high K⁺ medium maintained a high internal K⁺ concentration in the absence of cellular metabolism. When transferred to Krebs solutions containing different concentrations of Na⁺ they accumulated 5‐HT by a process that was related to the magnitudes of the internal and external Na⁺ concentrations. The results are consistent with the hypothesis that the spontaneous movement of ions through the platelet membrane is capable of providing, at least in part, the energy requirements for 5‐HT transport.