Measurement of endogenous Na<sup>+</sup>,K<sup>+</sup>‐ATPase inhibitors in human plasma and urine using high‐performance liquid chromatography

Crabos, Maryse; Wainer, Irving W.; Cloix, Jean‐François

doi:10.1016/0014-5793(84)80946-1

Cited by 33 publications

(8 citation statements)

References 16 publications

(7 reference statements)

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“…The effects of various concentrations of ouabain were tested in three different biological activities in addition to the binding of [ 3 H]ouabain to human erythrocytes: 1) the activity of dog kidney Na + ,K + -ATPase, 9 2) the binding of …”

Section: Other Assay Techniquesmentioning

confidence: 99%

The effects of urinary digitalislike factor on cultured vascular smooth muscle cells.

et al. 1988

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SUMMARY We attempted to purify a digitalislike factor from human urine. On the assumption that a natural ligand for the digitalis receptor should be searched for on the basis of the effects on intact cells, we used an inhibitory effect on the binding of [ Efforts by a number of laboratories to purify this factor have recently intensified. Several substances have been proposed as endogenous digitalislike factors, including unsaturated fatty acids, lysophosphatidylcholine, dehydroepiandrosterone sulfate, ascorbic acid, and mammalian lignans.4 " 8 However, of these compounds currently identified as having digitalislike activity, none appears to be the natural ligand of the digitalis receptor of Na + ,K + -adenosine triphosphatase (ATPase). We assumed that a natural ligand for the digitalis receptor should be searched for on the basis of the effects on intact cells. In this study, we used an inhibitory effect on [ 3 H]ouabain binding to human erythrocytes to monitor digitaiislike activity and partially purified a digitalislike factor from human urine. Furthermore, we examined the effects of the purified material on ion fluxes of cultured rat vascular smooth muscle cells. Materials and Methods Preparation of Crude [ 3 H]Ouabain Displacing ActivityHuman urine, approximately 4000 L each, was collected five times from normal male volunteers. Batches of 4000 L were treated on the day of collection with 50 L of Amberlite XAD2 preequilibrated with distilled water. [3 H]ouabain displacing activity (ODA) was eluted from Amberlite XAD2 with 50 L of 100% methanol and evaporated to dryness.

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Section: Other Assay Techniquesmentioning

confidence: 99%

The effects of urinary digitalislike factor on cultured vascular smooth muscle cells.

et al. 1988

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“…8 The plasma was resolved into three peaks with EDLC properties, and urine was resolved into two peaks. The latter had the same retention times as the first two of the three plasma EDLC peaks.…”

Section: Edlc From Human Urinementioning

confidence: 99%

Endogenous digitalislike compounds. A tentative update of chemical and biological studies.

Cloix

1987

Hypertension

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Endogenous digitalislike compound (or compounds) has been described as involved in some diseases. Questions remain concerning its chemical nature, origin, and biological properties. The methods of measuring the compound are based on biological properties of digitalis, mainly Na+, K+-adenosine triphosphatase (ATPase) inhibition and related properties. Chemically, digitalislike compound has been described as a peptide, as fatty acids, and as a steroid. Its origin could be the brain, particularly the hypothalamus and pituitary gland. The adrenal glands were also proposed as its origin. The reported biological properties of digitalislike compound are mainly dependent on Na+, K+-ATPase inhibition. No definitive conclusions can be drawn from the available data.

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“…32 Further confirmation of this observation is awaited with interest. Crabos et al 33 also used HPLC to fractionate plasma and urine in normal and hypertensive subjects. They found several peaks of Na + ,K + -ATPase inhibitory activity, some of which cross-reacted in a digoxin radioimmunoassay and were present in greater amounts in hypertensive subjects than in normal subjects.…”

Section: Plasmamentioning

confidence: 99%

The search for a hypothalamic Na+,K+-ATPase inhibitor.

Haber¹,

Haupert²

1987

Hypertension

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SUMMARY Accumulating experimental evidence suggests that natrjuresis in response to intravascular volume expansion is promoted by an endogenous regulator of Na + ,K + -adenosine triphosphatase (ATPase). Efforts to purify this substance by a number of laboratories have as yet been unsuccessful. The properties of partially purified inhibitors from plasma, urine, and tissue often fall to possess the characteristics thought to be consistent with those of a physiological regulator. These include potency (K, of approximately 1 nM), reversibility of inhibition, specificity for Na + ,K + -ATPase, and responsiveness to relevant physiological stimuli. Two rather different candidate substances, extracted from urine and hypotbalamus, have been purified to a high degree. Neither is a peptide, and both are of low molecular weight and resistant to acid hydrolysis. The substance from urine is rather nonpolar and interacts with digoxin-specific antibodies, while that from hypothalamus is polar and does not appear to share epitopes with the cardiac glycosides. On the serosal surface of the toad urinary bladder, the hypothalamic substance causes a reversible inhibition of Na + transport, inhibits rubidium uptake in red blood cells by acting on the membrane's exterior surface, inhibits binding of ouabain to purified Na + ,K + -ATPase, and reversibly inhibits hydrolysis of adenosine S'-triphosphate by the enzyme with a A', of 1.4 nM. The hypothalamic inhibitor may be differentiated from ouabain by their respective ionic requirements for optimal inhibition of enzymatic activity, and although both ouabain and the hypothalamic inhibitor fix Na + ,K + -ATPase in its Ej conformation, the hypothalamic inhibitor does not promote phosphoryiation of the enzyme by inorganic phosphate in the presence of

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Measurement of endogenous Na⁺,K⁺‐ATPase inhibitors in human plasma and urine using high‐performance liquid chromatography

Cited by 33 publications

References 16 publications

The effects of urinary digitalislike factor on cultured vascular smooth muscle cells.

The effects of urinary digitalislike factor on cultured vascular smooth muscle cells.

Endogenous digitalislike compounds. A tentative update of chemical and biological studies.

The search for a hypothalamic Na+,K+-ATPase inhibitor.

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Measurement of endogenous Na+,K+‐ATPase inhibitors in human plasma and urine using high‐performance liquid chromatography

Cited by 33 publications

References 16 publications

The effects of urinary digitalislike factor on cultured vascular smooth muscle cells.

The effects of urinary digitalislike factor on cultured vascular smooth muscle cells.

Endogenous digitalislike compounds. A tentative update of chemical and biological studies.

The search for a hypothalamic Na+,K+-ATPase inhibitor.

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Measurement of endogenous Na⁺,K⁺‐ATPase inhibitors in human plasma and urine using high‐performance liquid chromatography