Identification of 11,13-dihydroxy-14-octadecaenoic acid as a circulating Na+/K+-ATPase inhibitor

Lichtstein, David; Samuelov, S.; Gati, Irith; Félix, Arthur; Gabriel, Thomas F.; Deutsch, Joseph

doi:10.1677/joe.0.1280071

Cited by 14 publications

(4 citation statements)

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“…It is suggested that the material present in the lens and responsible for the digitalis-like activity is mainly 19-norbufalin and a peptide-(Thr-Gly-A1a)-conjugated 19-norbufalin ( Fig. 5).…”

Section: Discussionmentioning

confidence: 99%

“…The binding of ['Hlouabain to a rat brain synaptosomal fraction was carried out by a conventional filtration technique as previously described [19]. In brief; the reaction mixture (500 p1 final volume) contained the following constituents (final concentrations); SO mM Tris/HCI, pH 7.4,0.4 mM EDTA, 80 mM NaC1,4 mM MgS04, 2 mM ATP (Tris, vanadium free), ['Hlouabain (32 nM, 19.5 Ci/mmol; New England Nuclear) and other additions as indicated.…”

Section: Inhibition Of [3h]ouabain Bindingmentioning

confidence: 99%

“…Na', K+-ATPase activity in the rat brain microsomal fraction was determined as previously described [19]. Enzyme activity was measured by the colorimetric determination of inorganic phosphate after the incubation of microsomes (30 yg proteinheaction) at 37°C in a solution (final volume 500 y1) containing (final concentrations) 50 mM Tris/HCl, pH 7.4, 100 mM NaCI, 10 mM KCI, 4 mM MgCl, and 2 mM ATP (Tris, vanadium free).…”

Section: Inhibition Of Na+ K+-atpase Activitymentioning

confidence: 99%

“…Human cataractous lens nuclei were extracted and partially purified as described in Materials and Methods. ATPases activity was performed on rat brain microsomal membrane fraction [19]. Values are from a single experiment conducted in triplicates.…”

Section: Digitalis-like Activity In Human Cataractous Lenses and Normmentioning

confidence: 99%

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Identification of digitalis‐like compounds in human cataractous lenses

Lichtstein¹,

Gati²,

Samuelov³

et al. 1993

European Journal of Biochemistry

135

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Human cataractous lens nuclei extract inhibited, in a dose-dependent fashion, [3H]ouabain binding to rat brain synaptosomes and microsomal Na+-and K+-dependent adenosine triphosphate (Na+ , K+-ATPase) activity and interacted with anti-digoxin antibodies. The compounds responsible for these activities, termed digitalis-like compounds (DLC), were also detected in bovine, rat, cat and rabbit, normal, transparent lenses, but the levels were only 0.7-5.4% of the average levels in the cataractous human lenses. DLC from the human cataractous lenses were purified by a procedure consisting of organic extractions and batch chromatography followed by filtration through a 3000 Da cut-off filter and subsequent separations using reverse-phase high-performance liquid chromatography. The presence of DLC in the different fractions obtained in the chromatograms was monitored by their ability to inhibit [3H]ouabain binding and Na+, K+-ATPase activity. Based on chemical ionization mass spectrometry together with ultraviolet spectrometry and biological characterization, it is suggested that new bufodienolides, 19-norbufalin and 19-norbufalin peptide derivatives are responsible for the endogenous DLC activity. It is proposed that these compounds may regulate Na+, K+-ATPase activity in the lens under some physiological and pathological conditions.The Na+-and K+-dependent adenosine triphosphate (Na+, K'-ATPase) is an integral plasma membrane protein responsible for the maintenance of Na+ and K' concentration gradients in all eukaryotic cells. Since Na+, K'-ATPase has a high-affinity receptor for digitalis steroids, it has been postulated that there are endogenous ligands for these receptors which regulate the Na+, K' pump activity. Indeed, based on their ability to inhibit ['Hlouabain binding and Na+, K+-ATPase activity, digitalis-like compounds (DLC) have been shown to be present in the brain [l-31, heart [4] [24]. However, none of these compounds appears to be the natural ligand of the digitalis receptor of the Na+, K+-ATPase because of their limited specificity and affinity. Bufodienolides, which resemble the structure of the plant cardiac glycosides, have been identified in the plasma, brain and other tissues of toads [14, 15, 25, 261, however, their

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Section: Discussionmentioning

confidence: 99%

Section: Inhibition Of [3h]ouabain Bindingmentioning

confidence: 99%

Section: Inhibition Of Na+ K+-atpase Activitymentioning

confidence: 99%

Section: Digitalis-like Activity In Human Cataractous Lenses and Normmentioning

confidence: 99%

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