Stimulation of the Na+/K+ Pump Activity During Electrogenic Uptake of Acidic Amino Acid Transmitters by Rat Brain Synaptosomes

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Abstract
Addition of d‐aspartate, a substrate for the high‐affinity transport of acidic amino acid transmitters, to suspensions of rat brain synaptosomes increased the rate of O2 consumption, uptake of 86Rb, and transport of 2‐[3H]deoxyglucose. Stimulation of all three processes was abolished in the presence of ouabain. d‐Aspartate had no effect on respiration in the medium in which NaCl was replaced by choline chloride. The ratio of the ouabain‐sensitive increase in 86Rb uptake to that in O2 consumption was 12 to 1, which gives a calculated 86Rb(K+)/ATP of 2. It is concluded that electrogenic, high‐affinity transport of sodium‐d‐aspartate into synaptosomes stimulates the activity of the Na+/K+ pump through an increase in [Na+]i.