Isolation of an endogenous Na-pump specific inhibitor from normal pig urine: characterization and comparison with the inhibitor purified from bovine adrenal glands.
An endogenous Na-pump specific inhibitor has been purified to homogeneity from normal pig urine using Amberlite XAD-2 adsorption chromatography followed by five steps of reverse phase HPLC. Although most of the dose response curves for this purified Na-pump inhibitor, designated uroxin, in the various assay systems paralleled those of authentic ouabain and the specific Na-pump inhibitor previously purified from bovine adrenal glands (designated adrexin C), the cross-reactivity curve with anti-ouabain antibodies did not. The retention times of uroxin on various types of reverse phase HPLC columns were also different from those of plant-derived cardiotonic steroids and adrexin C. The cross-reaction curve of adrexin C was superimposable with that of ouabain, and adrexin C coeluted with ouabain from all of the HPLC columns tested. The results from physical and chemical characterization of both purified inhibitors suggest that uroxin is a novel Na-pump inhibitor which is structurally different from any of the known cardiotonic steroids or other substances previously reported to exhibit Na-pump inhibitory activity. The results also indicate that adrexin C is indistinguishable from ouabain. These results suggest that there are at least two different types of endogenous Na+,K(+)-ATPase inhibitors in the mammalian body.
Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN 37232-0146.
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Tamura
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Naruse
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Sakakibara
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Inagami
D000311:Adrenal Glands / Q000737:chemistry*; D000818:Animals; D001921:Brain / Q000201:enzymology; D002417:Cattle; D002850:Chromatography, Gel; D002851:Chromatography, High Pressure Liquid; D004912:Erythrocytes / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D008297:Male; D008970:Molecular Weight; D010446:Peptide Fragments; D010455:Peptides / Q000302:isolation & purification* / Q000378:metabolism / Q000494:pharmacology; D011333:Pro-Opiomelanocortin / Q000302:isolation & purification* / Q000378:metabolism / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D000254:Sodium-Potassium-Exchanging ATPase / Q000037:antagonists & inhibitors / Q000187:drug effects*; D013552:Swine; D014556:Urine / Q000737:chemistry*
D010446:Peptide Fragments; D010455:Peptides; C078895:joining peptide, pro-opiomelanocortin; D011333:Pro-Opiomelanocortin; D000254:Sodium-Potassium-Exchanging ATPase