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Buckalew VM. Endogenous digitalis-like factors: an overview of the history. Front Endocrinol (Lausanne) 2015; 6:49. [PMID: 25918512 PMCID: PMC4394700 DOI: 10.3389/fendo.2015.00049] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/09/2014] [Accepted: 03/24/2015] [Indexed: 12/22/2022] Open
Abstract
The sodium pump is a ubiquitous cell surface enzyme, a Na, K ATPase, which maintains ion gradients between cells and the extracellular fluid (ECF). The extracellular domain of this enzyme contains a highly conserved binding site, a receptor for a plant derived family of compounds, the digitalis glycosides. These compounds inhibit the enzyme and are used in the treatment of congestive heart failure and certain cardiac arrhythmias. The highly conserved nature of this enzyme and its digitalis receptor led to early suggestions that endogenous regulators might exist. Recent examination of this hypothesis emerged from research in two separate areas: the regulation of ECF volume by a natriuretic hormone (NH), and the regulation of peripheral vascular resistance by a circulating inhibitor of vascular Na, K ATPase. These two areas merged with the hypothesis that NH and the vascular Na, K ATPase inhibitor were in fact the same entity, and that it played a causative role in the pathophysiology of certain types of hypertension. The possibility that multiple endogenous digitalis-like factors (EDLFs) exist emerged from efforts to characterize the circulating enzyme inhibitory activity. In this review, the development of this field from its beginnings is traced, the current status of the structure of EDLFs is briefly discussed, and areas for future development are suggested.
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Affiliation(s)
- Vardaman M. Buckalew
- Medical Center Boulevard, Wake Forest School of Medicine, Winston Salem, NC, USA
- *Correspondence: Vardaman M. Buckalew, Medical Center Boulevard, Wake Forest School of Medicine, Winston Salem, NC 27157, USA e-mail:
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Tomaschitz A, Piecha G, Ritz E, Meinitzer A, Haas J, Pieske B, Wiecek A, Rus-Machan J, Toplak H, März W, Verheyen N, Gaksch M, Amrein K, Kraigher-Krainer E, Fahrleitner-Pammer A, Pilz S. Marinobufagenin in essential hypertension and primary aldosteronism: a cardiotonic steroid with clinical and diagnostic implications. Clin Exp Hypertens 2014; 37:108-15. [PMID: 24785704 DOI: 10.3109/10641963.2014.913604] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
BACKGROUND The cardiotonic steroid marinobufagenin (MBG) is increasingly suggested to be responsible for some of the cardiovascular injury that has been previously attributed to aldosterone. We examined the clinical correlates of circulating MBG concentrations in hypertensive patients and tested the hypothesis that MBG serves as a reliable diagnostic tool for detecting primary aldosteronism (PA). METHODS Plasma MBG concentrations (mean: 0.51±0.25 nmol/l) were measured in the morning fasting samples in 20 patients with PA and 20 essential hypertensive (EH) controls matched for age, sex, body mass index, renal function, urinary sodium and intake of antihypertensive medication (mean age: 51.6 years; 52.2% women). RESULTS Overall, plasma MBG was directly correlated with plasma aldosterone, aldosterone to active renin ratio (AARR), diastolic blood pressure, mean carotid intima-media thickness, serum sodium, urinary protein to creatinine ratio and inversely with serum potassium levels. Plasma MBG levels were significantly higher in patients with PA compared to EH (mean: 0.68±0.12 versus 0.35±0.24 nmol/l; p<0.001). ROC analysis yielded a greater AUC for plasma MBG compared to the AARR, PAC and serum potassium levels for detecting PA. Youden's Index analyses yielded the optimal plasma MBG cut-off score for diagnosing PA at >0.49 nmol/l with specificity and sensitivity values of 0.85 and 0.95, respectively, which were higher than those at the optimum AARR cut-off at >3.32 ng/dl/µU/ml. CONCLUSIONS In a well-characterized cohort, values of plasma MBG were significantly related to clinical correlates of cardiovascular and renal disease. Plasma MBG emerged as a valuable alternative to the AARR for screening of PA.
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Fedorova OV, Shapiro JI, Bagrov AY. Endogenous cardiotonic steroids and salt-sensitive hypertension. Biochim Biophys Acta Mol Basis Dis 2010; 1802:1230-6. [PMID: 20347967 DOI: 10.1016/j.bbadis.2010.03.011] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2010] [Revised: 03/18/2010] [Accepted: 03/20/2010] [Indexed: 12/12/2022]
Abstract
Endogenous cardiotonic steroids (CTS), also called digitalis like factors, have been postulated to play important roles in pathogenesis of hypertension for nearly half of a century. For the past 50 years biomedical scientists have been in quest of an unidentified factor or hormone that both increases blood pressure and renal sodium excretion; this "natriuretic hormone" was, in fact, postulated to interact with the Na/K-ATPase. Recent discoveries have led to the identification of steroid molecules which are present in humans, rodents and amphibians, and which, in a complex manner, interact with each other and with the other systems that regulate renal salt handling and contribute to the salt-sensitivity of blood pressure. Recent findings include the specific identification of endogenous cardenolide (endogenous ouabain) and bufadienolide (marinobufagenin) CTS in humans along with the delineation of mechanisms by which CTS can signal through the Na/K-ATPase. Although CTS were first considered important in the regulation of renal sodium transport and arterial pressure, more recent work implicates these hormones in the central regulation of blood pressure and regulation of cell growth, and development of cardiovascular and renal fibrosis in particular.
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Affiliation(s)
- Olga V Fedorova
- National Institute on Aging, National Institutes of Health, Baltimore, MD, USA
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Bagrov AY, Shapiro JI, Fedorova OV. Endogenous cardiotonic steroids: physiology, pharmacology, and novel therapeutic targets. Pharmacol Rev 2009; 61:9-38. [PMID: 19325075 PMCID: PMC2763610 DOI: 10.1124/pr.108.000711] [Citation(s) in RCA: 379] [Impact Index Per Article: 25.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Endogenous cardiotonic steroids (CTS), also called digitalis-like factors, have been postulated to play important roles in health and disease for nearly half a century. Recent discoveries, which include the specific identification of endogenous cardenolide (endogenous ouabain) and bufadienolide (marinobufagenin) CTS in humans along with the delineation of an alternative mechanism by which CTS can signal through the Na(+)/K(+)-ATPase, have increased the interest in this field substantially. Although CTS were first considered important in the regulation of renal sodium transport and arterial pressure, more recent work implicates these hormones in the regulation of cell growth, differentiation, apoptosis, and fibrosis, the modulation of immunity and of carbohydrate metabolism, and the control of various central nervous functions and even behavior. This review focuses on the physiological interactions between CTS and other regulatory systems that may be important in the pathophysiology of essential hypertension, preeclampsia, end-stage renal disease, congestive heart failure, and diabetes mellitus. Based on our increasing understanding of the regulation of CTS as well as the molecular mechanisms of these hormone increases, we also discuss potential therapeutic strategies.
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Affiliation(s)
- Alexei Y Bagrov
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of Health, 5600 Nathan Shock Dr., Baltimore, MD 21224, USA.
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Haddy FJ, Pamnani MB. Role of ouabain-like factors and Na-K-ATPase inhibitors in hypertension--some old and recent findings. Clin Exp Hypertens 1998; 20:499-508. [PMID: 9682906 DOI: 10.3109/10641969809053228] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Three lines of evidence led to our suggestion in 1976 that sodium pump inhibitors are involved in volume expanded hypertension. These were 1) pressor activity of low renin hypertensive blood 2) natriuretic and sodium pump inhibiting activities of volume expanded blood and 3) potassium vasoactivity which was blocked by ouabain and suppressed potassium vasodilatation, myocardial Na-K-ATPase, and artery, vein and WBC sodium pumps in low renin hypertension. This led to bioassay of plasma from acutely volume expanded dogs and from dogs with one-kidney, one wrapped hypertension for sodium pump inhibiting activity that acts on arteries. Positive results were reported in 1980. The assay was also positive in rats with one-kidney, one clip and reduced renal mass hypertension (but not in rats with spontaneous or salt sensitive hypertension) and in humans with acute volume expansion and low renin essential hypertension (but not in humans with normal renin hypertension). Thus the inhibitor which acts on the sodium pump in arteries appears to be present only in low renin hypertension.
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Affiliation(s)
- F J Haddy
- Department of Physiology, Uniformed Services University, Bethesda, MD 20814, USA
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Weiler EW, Gonick HC, Prins BA, Purdy RE, Weber MA. Characterization of a low molecular weight Na-K-ATPase inhibitor of urinary origin. Am J Med Sci 1994; 307:27-35. [PMID: 8291503 DOI: 10.1097/00000441-199401000-00005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
It has been demonstrated that expansion of extracellular fluid volume induces the release of a low-molecular-weight natriuretic and sodium-potassium-activated adenosine triphosphatase inhibiting hormone (NKAI). In this study, we used a highly purified hormone extracted from pooled hypertensive urines (u-NKAI). Like ouabain, this compound was found to be a potent inhibitor of the sodium-potassium-activated adenosine-triphosphatase and potassium-stimulated paranitrophenyl phosphatase enzyme systems as well as a vasoconstrictor in vitro. In contrast to ouabain, which is a competitive inhibitor of both enzyme systems with respect to potassium, u-NKAI is noncompetitive. Furthermore, u-NKAI differs from ouabain by its lack of cross-reactivity with digoxin antibodies. In addition, whereas ouabain binds to both high-affinity and low-affinity binding sites on the sodium-potassium-activated adenosine-triphosphatase enzyme in the absence of potassium, u-NKAI binds only to the low-affinity binding sites. This study demonstrates that the highly purified u-NKAI, although ouabain-like in certain respects, is not an "endogenous ouabain."
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Affiliation(s)
- E W Weiler
- Trace Element Laboratory, Division of Nephrology/Department of Medicine, Cedars-Sinai Medical Center, Los Angeles, CA 90048
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Lichtstein D, Samuelov S, Gati I, Wechter WJ. Digitalis-like compounds in animal tissues. J Basic Clin Physiol Pharmacol 1992; 3:269-92. [PMID: 1339222 DOI: 10.1515/jbcpp.1992.3.4.269] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The Na+, K+ activated adenosine triphosphatase is present in the membrane of eukaryotic cells and represents a major pathway for Na+ and K+ transport across the plasma membrane. Cardiac glycosides such as ouabain or digoxin suppress this enzyme activity by binding to a specific receptor on the membrane. Studies conducted in this and other laboratories have proven the existence of digitalis-like compounds in animal tissues which may serve as in vivo regulators of the Na+, K(+)-pump activity. This review summarizes the attempts to identify these compounds from animal tissues and examines the potential physiological role of some of the identified compounds.
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Affiliation(s)
- D Lichtstein
- Department of Physiology, Hebrew University-Hadassah Medical School, Jerusalem, Israel
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Yamada H, Ihara N, Takahashi H, Yoshimura M, Sano Y. Distribution of the endogenous digitalis-like substance (EDLS)-containing neurons labeled by digoxin antibody in hypothalamus and three circumventricular organs of dog and macaque. Brain Res 1992; 584:237-43. [PMID: 1325245 DOI: 10.1016/0006-8993(92)90900-t] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Endogenous digitalis-like substance (EDLS) is a newly discovered humoral agent which causes sodium-diuresis. EDLS is well known to have inhibitory activity to Na+,K(+)-ATPase and cross-immunoreactivity to digoxin antibody; however, its precise chemical structure has not yet been determined. We had previously developed a histochemical technique for EDLS, i.e., digoxin-immunohistochemistry, and demonstrated that EDLS was produced in the hypothalamic neurons. In the present study, the distribution of EDLS-containing neurons in the hypothalamus of dog and macaque was investigated using this technique, because anti-EDLS antibody cannot be obtained yet. In both species, EDLS neuronal somata were mainly localized in the paraventricular nucleus and the supraoptic nucleus and its accessory nuclei. A number of somata were also scattered in the other hypothalamic areas. The processes of these neurons ran from the area where the somata were located, through the lateral and basal area of the hypothalamus, to the infundibulum. These nerve fibers with varicosities were associated with the primary capillaries of hypophysial portal veins. A few immunopositive nerve fibers were also seen in the pituitary posterior lobe of both species. Intensive immunoreactivities were observed in the subfornical organ and organum vasculosum laminae terminalis. There were no differences between dog and macaque.
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Affiliation(s)
- H Yamada
- Department of Anatomy, Shiga University of Medical Science, Otsu, Japan
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Vargas F, Andrade JL, Jódar E, Castillo MA, Luna JD, Haro JM. Urinary excretion of digoxin-like immunoreactive factor and arginine-vasopressin in rats after several osmotic loads. Life Sci 1991; 49:611-5. [PMID: 1865755 DOI: 10.1016/0024-3205(91)90260-i] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Urinary digoxin-like immunoreactive factor (DLIF), arginine-vasopressin (AVP) and other urinary parameters were investigated under normal conditions and after the i.p. injection of the following solutions: distilled water, isotonic and hypertonic NaCl, NaHCO3, KCl and urea, at a rate of 3 ml/100 g body weight. The measurement of digoxin-like immunoreactivity by two different radioimmunoassays showed that DLIF was stimulated by all volume loads regardless of the presence or absence of osmolar compounds. This dissociation between DLIF and urinary sodium excretion suggests that DLIF may not constitute the natriuretic hormone. Moreover, a dissociation between DLIF and AVP excretion also were found, which speaks against the hypothesis of a common mechanism of stimulation for both substances.
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Affiliation(s)
- F Vargas
- Departamento de Bioquímica, Facultad de Medicina, Universidad de Granada, Spain
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Chapter 17 Sodium Pump Regulation by Endogenous Inhibitors. ACTA ACUST UNITED AC 1989. [DOI: 10.1016/s0070-2161(08)60021-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/30/2023]
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Inagami T, Tamura M. Purification and characterization of specific endogenous ouabainlike substance from bovine adrenal. Am J Med Sci 1988; 295:400-5. [PMID: 2834953 DOI: 10.1097/00000441-198804000-00030] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Endogenous inhibitors of Na, K-ATPase have been implicated in the pathogenesis of salt-induced hypertension. Despite an intensive search, the inhibitor(s) have long remained elusive. We have been able to purify such an inhibitor from methanol extracts of bovine adrenal glands by multiple steps of high-performance liquid chromatography (HPLC). This compound showed striking similarity to the cardiac glycoside ouabain in its dose dependency in the inhibition of Na, K-ATPase and Na-pump activity, competitive binding to the ouabain-binding site, and dependence of these effects on K+ concentration. These results indicate that vertebrate animals contain a regulator of Na, K-ATPase.
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Affiliation(s)
- T Inagami
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee 37232
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Crabos M, Grichois ML, Guicheney P, Wainer IW, Cloix JF. Further biochemical characterization of an Na+ pump inhibitor purified from human urine. EUROPEAN JOURNAL OF BIOCHEMISTRY 1987; 162:129-35. [PMID: 3028785 DOI: 10.1111/j.1432-1033.1987.tb10552.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
An increase in endogenous Na+,K+-ATPase inhibitor(s) with digitalis-like properties has been reported in chronic renal insufficiency, in Na+-dependent experimental hypertension and in some essential hypertensive patients. The present study specifies some properties and some biochemical characteristics of a semipurified compound from human urine having digitalis-like properties. The urine-derived inhibitor (endalin) inhibits Na+,K+-ATPase activity and [3H]-ouabain binding, and cross-reacts with anti-digoxin antibodies. The inhibitory effect on ATPases of endalin is higher on Na+,K+-ATPase than on Mg2+-ATPase and Ca2+-ATPase. The mechanism of endalin action on highly purified Na+,K+-ATPase was compared to that of ouabain and was similar in that it reversibly inhibited Na+,K+-ATPase activity; it inhibited Na+,K+-ATPase non-competitively with ATP; its inhibitory effect was facilitated by Na+; K+ decreased its inhibitory effect on Na+,K+-ATPase; it competitively inhibited ouabain binding to the enzyme; its binding was maximal in the presence of Mg2+ and Pi; it decreased the Na+ pump activity in human erythrocytes; it reduced serotonin uptake by human platelets; and it was diuretic and natriuretic in rat bioassay. The endalin differed from ouabain in only three aspects: its inhibitory effect was not really specific for Na+,K+-ATPase; its binding to the enzyme was undetectable in the presence of Mg2+ and ATP; it was not kaliuretic in rat bioassay. Endalin is a reversible and partial specific inhibitor of Na+,K+-ATPase, its Na+,K+-ATPase inhibition closely resembles that of ouabain and it could be considered as one of the natriuretic hormones.
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Masugi F, Ogihara T, Hasegawa T, Kumahara Y. Ouabain-like and non-ouabain-like factors in plasma of patients with essential hypertension. CLINICAL AND EXPERIMENTAL HYPERTENSION. PART A, THEORY AND PRACTICE 1987; 9:1233-42. [PMID: 3040306 DOI: 10.3109/10641968709160046] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Circulating inhibitor of Na+,K+-ATPase and ouabain-like immunoreactivity were studied in patients with essential hypertension. In the plasma of patients, two types of Na+,K+-ATPase inhibitors (ouabain-like and non-ouabain-like inhibitors) and ouabain-like immunoreactivity were detected. Ouabain-like inhibitor was clearly detected at a low KCl concentration (0.1 mM) in the assay buffer, and non-ouabain-like inhibitor was detected at a high KCl concentration (10 mM). The plasma level of ouabain-like inhibitor correlated significantly with that of ouabain-like immunoreactivity (p less than 0.001) and with a mean blood pressure (p less than 0.01). The plasma level of non-ouabain-like inhibitor was not correlated with the levels of either ouabain-like immunoreactivity or mean blood pressure. The level of plasma ouabain-like inhibitor did not correlate with that of plasma non-ouabain like inhibitor. Both ouabain-like inhibitor and ouabain-like immunoreactivity in the plasma of patients with essential hypertension were significantly higher than those in normotensive subjects, but the plasma level of non-ouabain-like inhibitor in patients with essential hypertension was not higher than that in normotensive subjects. These results suggest that the plasma from patients with essential hypertension contains ouabain-like factor(s) which is important to maintain the high blood pressure.
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HAUPERT GARNERT, CHEN EDWARD, RAY SWAPNA, CANTIELLO HORACIOF. Hypothalamic Factor Regulates Sodium Pump Activity in Cultured Renal Tubular Epithelial Cells. Ann N Y Acad Sci 1986. [DOI: 10.1111/j.1749-6632.1986.tb54441.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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HAUPERT GARNERT, CHEN EDWARD, RAY SWAPNA, CANTIELLO HORACIOF. Hypothalamic Factor Regulates Sodium Pump Activity in Cultured Renal Tubular Epithelial Cells. Ann N Y Acad Sci 1986. [DOI: 10.1111/j.1749-6632.1986.tb46595.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Kramer HJ, Baecker A, Weiler E, Liddiard C. Studies on ouabain-like endogenous natriuretic factors in human urine. Inhibition of Na-K-ATPase and 3H-ouabain binding. KLINISCHE WOCHENSCHRIFT 1986; 64:760-6. [PMID: 3020314 DOI: 10.1007/bf01734344] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
An endogenous inhibitor of sodium transport and of the Na-K-ATPase enzyme was previously detected in the small molecular weight postsalt fraction SIV of serum from saline-loaded rats after gel filtration on Sephadex G-25. In addition, a natriuretic factor present in this fraction of urine from salt-loaded subjects was found to bind to a specific digoxin antibody. Therefore, in the present study the small molecular weight natriuretic and digoxin antibody-binding activities present in the urine of salt-loaded healthy volunteers were purified by reverse-phase chromatography and by immunoprecipitation with the digoxin antibody and were studied for their in vitro effects on Na-K-ATPase derived from hog cerebral cortex. Na-K-ATPase inhibitory activities were found to roughly parallel the natriuretic activities at the various stages of purification. After reverse-phase chromatography, the material of fraction SIV which was bound to the digoxin antibody revealed the highest specific natriuretic activity of 3.95 +/- 0.29 mumol/min X mg injected material and showed strongest inhibition of the enzyme with I50 at a concentration of 0.08 microgram/ml, as compared with 2.4 micrograms/ml of the original postsalt urine fraction SIV. Fraction SIV revealed a noncompetitive inhibition of the enzyme with respect to potassium, but also significantly inhibited 3H-ouabain binding to the enzyme. Thus, the natriuretic substance(s) present in the urine of salt-loaded healthy subjects exhibit a potent inhibitory effect on the Na-K-ATPase enzyme which is similar, but not identical to that of ouabain.
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Abstract
Recent research has demonstrated the presence of endogenous compounds in blood and urine that crossreact with antibodies raised against digoxin. Given the widespread therapeutic use of digoxin and its being monitored clinically by immunoassay, such digoxin-like immunoreactive compounds pose significant diagnostic and interpretive problems. Serum levels of this factor(s) approaching therapeutic digoxin levels have been found in digoxin-free patients in renal failure, pregnant women, and newborns. The compound is incompletely characterized; however, existing data suggest that it is a small, neutral, nonpeptidic compound. In serum it is highly protein bound, and alterations in this binding appear to give rise to the false-positive assay results. The urinary form is probably conjugated. Digoxin-like immunoreactive substances may play a role in volume homeostasis and appear associated with essential and pregnancy-induced hypertension. If such roles are primary, measurement of digoxin-like immunoreactive substances may prove to be of value in and of itself.
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Evidence for differences in the sensitivity to ouabain of NaK-ATPase along the nephrons of rabbit kidney. J Biol Chem 1986. [DOI: 10.1016/s0021-9258(17)36042-8] [Citation(s) in RCA: 61] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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Clough DL. Inhibition of rat cardiac and renal Na+,K+-ATPase by high sodium concentrations and vanadate. Life Sci 1985; 37:799-807. [PMID: 2993776 DOI: 10.1016/0024-3205(85)90514-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
In the present study, rat renal Na+,K+-ATPase was found to be more sensitive to inhibition by high Na+ concentrations (100-400 mM) than was rat cardiac Na+,K+-ATPase. K+ was more effective in reversing the inhibition by Na+, of cardiac relative to renal Na+,K+-ATPase. Rat renal Na+,K+-ATPase was also more sensitive than cardiac Na+,K+-ATPase to inhibition by vanadate over this range of Na+ concentrations. These results support the hypothesis that vanadate may selectively regulate Na+,K+-ATPase in the kidney, and they may also help explain the natriuretic and diuretic effects of vanadate in rats. Inhibition of renal Na+,K+ATPase by Na+, may also help explain, in part, the natriuretic and diuretic effects of acute saline loading.
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Hnatowich M, Labella F. Endogenous digitalis-like factors: in vitro comparison of biological and immunological activities of peptide and steroid candidates. Eur J Pharmacol 1984; 106:567-75. [PMID: 6097462 DOI: 10.1016/0014-2999(84)90060-8] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Endogenous substances that modulate the activity of (Na+ + K+)-ATPase through interaction at the cardiac glycoside site have been postulated. Reports of digitalis-like biological and immunological activity exhibited by certain ACTH/MSH peptides and 14-OH steroids make these compounds potential candidates as endogenous digitalis-like factors. We tested several ACTH/MSH peptides and 14 alpha-OH steroids in four in vitro assays and detected no significant cardiac glycoside-like activity. On the other hand, chlormadinone acetate, a progesterone derivative shown to bind with high affinity to the digitalis receptor, was nearly equipotent to digoxigenin in a [3H]ouabain radioreceptor assay. In a [3H]digoxin radioimmunoassay, however, digoxigenin and digoxin were equipotent but chlormadinone acetate was inactive. A clear dissociation between radioreceptor assay and radioimmunoassay activity was also observed using 15 beta-OH-progesterone. Our findings indicate that (a) ACTH/MSH peptides and 14 alpha-OH steroids are not viable candidates as endogenous digitalis-like factors, (b) digoxin antibodies are not necessarily directed at molecular determinants critical for biological activity, and (c) among the compounds reported to exhibit digitalis-like activity and postulated to share structural features with an endogenous steroidal digitalis-like factor, only chlormadinone acetate and its congeners appear to constitute tenable models.
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Endogenous Glycoside-Like Substances. ACTA ACUST UNITED AC 1983. [DOI: 10.1016/s0070-2161(08)60643-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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Gonick HC. Pathophysiology of human proximal tubular transport defects. KLINISCHE WOCHENSCHRIFT 1982; 60:1201-11. [PMID: 6292569 DOI: 10.1007/bf01716723] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The generalized proximal tubular transport abnormalities comprising the Fanconi syndrome (glycosuria, generalized aminoaciduria, the proximal form of renal tubular acidosis, and increased renal clearance of phosphate, urate, calcium, magnesium, and potassium) may be ascribed to interference with "sodiumlinked" active transport. Evidence is presented that the majority of conditions known to cause Fanconi syndrome in man or experimental animals are associated with inhibitors of the renal Na-K-ATPase-ATP transport system.
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Haddy FJ. Humoral factors and the sodium-potassium pump in low renin hypertension. KLINISCHE WOCHENSCHRIFT 1982; 60:1254-7. [PMID: 6292571 DOI: 10.1007/bf01716733] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Recent studies suggest that sodium dependent low renin hypertension results in part from the release of a ouabain-like factor, perhaps natriuretic hormone, from the brain. This humoral factor inhibits Na+, K+-ATPase and hence the active pumping of sodium and potassium in the muscle cells of blood vessels and heart. The pump suppression causes increased contractile activity and hence increased arterial blood pressure. In the muscle cells of the blood vessels, the increased contractile activity appears to be related to membrane depolarization.
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De Pover A, Castañeda-Hernández G, Godfraind T. Water versus acetone-HCl extraction of digitalis-like factor from guinea-pig heart. Biochem Pharmacol 1982; 31:267-71. [PMID: 6277341 DOI: 10.1016/0006-2952(82)90224-6] [Citation(s) in RCA: 33] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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McPartland RP, Rapp JP. (Na+,K+)-activated adenosinetriphosphatase and hypertension in DAHL salt- sensitive and -resistant rats. CLINICAL AND EXPERIMENTAL HYPERTENSION. PART A, THEORY AND PRACTICE 1982; 4:379-91. [PMID: 6280903 DOI: 10.3109/10641968209060750] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
(Na+,K+)-ATPase activity was compared in Dahl salt-sensitive (S) and salt-resistant (R) rats. When S and R rats were maintained on 1% NaCl diet their blood pressures at 5 weeks of age were similar and their renal microsomal (Na+,K+)-ATPase activities were also similar. At 6 months of age, on 1% NaCl diet, S rats have markedly elevated blood pressure compared to R and renal microsomal (Na+,K+)-ATPase activity was suppressed in S compared to R. Feeding 8% NaCl diet for 5 weeks induced hypertension in young S rats but failed to alter renal or brain (Na+,K+)-ATPase activity. Heart (Na+,K+)- ATPase activity was elevated in S compared to R rats regardless of salt intake of blood pressure. It appears unlikely that mutations in the structural locus for the renal (Na+,K+)-ATPase molecule are involved in the strain specific differences in susceptibility to salt-induced hypertension since the physical-chemical properties of the enzyme from the two strains were found to be similar. Since renal (Na+,K+)-ATPase activities were unchanged by salt feeding and resultant blood pressure changes in young S rats, the suppressed renal (Na+,K+)-ATPase activity seen only in old S rats is probably a response to prolonged renal damage and not a response to "natriuretic factors." Elevated heart (Na+,K+)-ATPase in S-rat hearts is unexplained.
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Kramer HJ. Natriuretic hormone - a circulating inhibitor of sodium- and potassium-activated adenosine triphosphatase. Its potential role in body fluid and blood pressure regulation. KLINISCHE WOCHENSCHRIFT 1981; 59:1225-30. [PMID: 6273645 DOI: 10.1007/bf01747753] [Citation(s) in RCA: 35] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Expansion of the extracellular fluid volume (ECFV) promotes the release of a small molecular weight (less than or equal to 1,000 Daltons) humoral natriuretic factor. The resulting natriuresis is accompanied by inhibition of renal cortical tissue and red blood cell Na-K-ATPase activity. This transport inhibitor, presumably an acidic peptide derived from a larger precursor molecule, was so far recovered from the serum and urine of rat, dog, and man, and from renal cortical tissue homogenate. Using Sephadex G-25 gel chromatography the inhibitor is eluted in the post-salt fraction IV. Its natriuretic action is demonstrated by bioassay methods, it depresses sodium transport of isolated amphibian membranes and inhibits Na-K-ATPase enzyme activity in vitro. The inhibitor isolated from human urine binds to specific antibodies against digoxin. This natriuretic factor is absent in patients with arterial hypotension and in edematous patients with secondary aldosteronism. In contrast, high inhibitory activity is found in patients with primary aldosteronism, a condition which represents the most classical type of low renin volume-dependent hypertension. Since enzyme inhibition by this humoral endogenous agent probably extends to various Na-K-ATPase-dependent transport systems including vascular smooth muscle fibers, depression of their Na-K pump will raise intracellular concentrations of sodium and calcium and thereby induce vasoconstriction. It is therefore tempting to speculate that the natriuretic hormone plays an important role in the pathogenesis of volume-dependent arterial hypertension.
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Favre H, Bricker NS. The pathology of marginal renal function. Rev Physiol Biochem Pharmacol 1981; 91:1-43. [PMID: 7031819 DOI: 10.1007/3-540-10961-7_1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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Gruber KA, Whitaker JM, Buckalew VM. Endogenous digitalis-like substance in plasma of volume-expanded dogs. Nature 1980; 287:743-5. [PMID: 6253813 DOI: 10.1038/287743a0] [Citation(s) in RCA: 341] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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Born GV. Chlorpromazine in prophylaxis of myocardial infarction. Lancet 1979; 1:1413-4. [PMID: 87881 DOI: 10.1016/s0140-6736(79)92056-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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Wilkinson SP, Poston L, Williams R. Chlorieuretic or natriuretic hormone. Lancet 1979; 1:1414. [PMID: 87883 DOI: 10.1016/s0140-6736(79)92057-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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Kramer HJ, Bäcker A, Krück F. Antinatriferic activity in human plasma following acute and chronic salt-loading. Kidney Int 1977; 12:214-22. [PMID: 926613 DOI: 10.1038/ki.1977.103] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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