Effect of Na+, K+-ATPase modifiers on high-affinity ouabain binding determined by quantitative autoradiography
✍ Scribed by Dr. M. Antonelli; T. Casillas; G. Rodríguez de Lores Arnaiz
- Publisher
- John Wiley and Sons
- Year
- 1991
- Tongue
- English
- Weight
- 769 KB
- Volume
- 28
- Category
- Article
- ISSN
- 0360-4012
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✦ Synopsis
There is growing evidence on the existence of endogenous ouabain-like factors that modulate Na+ ,K+-ATPase activity. In this laboratory, two soluble subfractions (peaks I and 11) were previously separated from rat cerebral cortex, which had opposite effects on Na+ ,K+ -ATPase activity. Peak I stimulated and peak I1 inhibited the enzyme (Rodriguez de Lores Arnaiz and Antonelli de Gomez de Lima, Neurochem Res 11:933-947, 1986). The same effects are now reported for K+ -p-nitrophenyphosphatase activity. Localization of high-affinity ouabain binding in rat brain was done by quantitative autoradiography using a microcomputer digital imaging system. Peak I did not modify, whereas peak I1 blocked ouabain binding in areas 3-4 of cerebral cortex, dentate gyrus, stria terminalis, thalamic nuclei, and basal ganglia. Similar results were obtained when ouabain binding was determined in rabbit cerebral cortex and by a conventional filtration assay in nerve ending membranes obtained from rat cerebral cortex. These results favour the idea that the factor present in peak I1 fraction might behave as an ouabain-like substance.