Differential properties between an endogenous brain Na+, K(+)-ATPase inhibitor and ouabain.
By means of a Sephadex G-50 column and anionic exchange HPLC a cerebral cortex soluble fraction (II-E) which highly inhibits neuronal Na(+)-K(+)-ATPase activity has been previously obtained. Herein, II-E properties are compared with those of the cardenolide ouabain, the selective and specific Na+, K(+)-ATPase inhibitor. It was observed that alkali treatment destroyed II-E but not ouabain inhibitory activity. II-E presented a maximal absorbance at 265 nm both at pH 7 and pH 2 which diminished at pH 10. Ouabain showed a maximum at 220 nm which was not altered by alkalinization. II-E was not retained in a C-18 column, indicating its hydrophilic nature, whereas ouabain presented a 26-min retention time in reverse phase HPLC. Therefore, it is concluded that the inhibitory factor present in II-E is structurally different to ouabain.
Peña
C
C
Instituto de Química y Fisicoquimica Biológicas, Facultad de Farmacia y Bioquímica, Buenos Aires, Argentina.
Rodríguez de Lores Arnaiz
G
G
D009597:4-Nitrophenylphosphatase / Q000378:metabolism; D000818:Animals; D001921:Brain / Q000201:enzymology*; D002540:Cerebral Cortex / Q000737:chemistry; D002850:Chromatography, Gel; D002851:Chromatography, High Pressure Liquid; D005260:Female; D006863:Hydrogen-Ion Concentration; D008297:Male; D010042:Ouabain / Q000737:chemistry / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D000254:Sodium-Potassium-Exchanging ATPase / Q000037:antagonists & inhibitors*; D013056:Spectrophotometry, Ultraviolet; D013574:Synaptosomes / Q000201:enzymology
D010042:Ouabain; D009597:4-Nitrophenylphosphatase; D000254:Sodium-Potassium-Exchanging ATPase