Kinetics of Na+, K+-ATPase Inhibition by a Rat Brain Endogenous Factor (II-E) |
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Authors: | Herbin Teresa Peña Clara de Lores Arnaiz Georgina Rodríguez |
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Affiliation: | (1) Instituto de Biología Celular y Neurociencias Prof. Eduardo De Robertis, Facultad de Medicina, Universidad de Buenos Aires, Paraguay 2155, 1121 Buenos Aires;(2) Facultad de Farmacia y Bioquímica, Instituto de Química y Fisicoquímica Biológicas, Junín 956, 1113 Buenos Aires, Argentina |
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Abstract: | Previous work from this laboratory led to the isolation by gel filtration and anionic exchange HPLC of a rat brain fraction named II-E, which highly inhibits synaptosomal membrane Na+, K+-ATPase activity. In this study we evaluated the kinetics of such inhibition and found that inhibitory potency was independent of Na+(1.56–200 mM), K+(1.25–40 mM), or ATP (1–8 mM) concentration. Hanes-Woolf plots indicated that II-E decreases Vmax but does not alter KMvalue, and suggested uncompetitive inhibition for Na+, K+or ATP. However, II-E became a stimulator at 0.5 mM ATP concentration. It is postulated that this brain factor may modulate ionic transport at synapses, thus participating in central neurotransmission. |
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Keywords: | Na+, K+-ATPase synaptosomal membranes endogenous inhibitor brain soluble factor |
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