How many endobains are there?
Oxidative metabolism is very active in brain, where large amounts of chemical energy as ATP molecules are consumed, mostly required to maintain cellular Na+/K+ gradients through the participation of the sodium pump (Na+,K+-ATPase), whose activity is selectively and potently inhibited by the alkaloid ouabain. Na+/K+ gradients are involved in nerve impulse propagation, in neurotransmitter release and cation homeostasis in the nervous system. Likewise, enzyme activity modulation is crucial for maintaining normal blood pressure and cardiovascular contractility as well as renal sodium excretion. The present article reviews the progress in disclosing putative ouabain-like substances, examines their denomination according to different research teams, tissue or biological fluid sources, extraction and purification, assays, biological properties and chemical and biophysical features. When data is available, comparison with ouabain itself is mentioned. Likewise, their potential action in normal physiology as well as in experimental and human pathology is summarized.
Rodríguez de Lores Arnaiz
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Instituto de Biología Celular y Neurociencias Prof. Eduardo De Robertis, PROBICENE-CONICET, Facultad de Medicina, Universidad de Buenos Aires, Paraguay, Buenos Aires, Argentina. grodrig@ffyb.uba.ar
D000255:Adenosine Triphosphate / Q000378:metabolism*; D000818:Animals; D001685:Biological Factors / Q000145:classification / Q000378:metabolism*; D001921:Brain / Q000378:metabolism*; D006801:Humans; D010042:Ouabain / Q000031:analogs & derivatives* / Q000378:metabolism*; D011188:Potassium / Q000378:metabolism; D012964:Sodium / Q000378:metabolism; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism
D001685:Biological Factors; D010042:Ouabain; D000255:Adenosine Triphosphate; D012964:Sodium; D000254:Sodium-Potassium-Exchanging ATPase; D011188:Potassium