1
|
Lai X, Wen H, Yang T, Qin F, Zhong X, Pan Y, Yu J, Huang J, Li J. Effects of renal denervation on endogenous ouabain in spontaneously hypertensive rats. Acta Cir Bras 2023; 37:e371102. [PMID: 36629529 PMCID: PMC9829196 DOI: 10.1590/acb371102] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2022] [Accepted: 10/12/2022] [Indexed: 01/11/2023] Open
Abstract
PURPOSE To investigate the role of renal denervation (RDN) on endogenous ouabain (EO) secretion in spontaneously hypertensive rats (SHR). METHODS Sixteen 12-week-old male SHR were randomly separated into the renal denervation group (RDNX group) and sham operation group (sham group), and eight age-matched Wistar Kyoto rats (WKY) were served as control group. EO concentrations, the Na+- K+-ATPaseactivity, and the expression of Na+-K+-ATPase were assessed. RESULTS EO levels in serum, kidneys and hypothalamus of sham group were higher than in RDNX group (p < 0.05). Renal Na+-K+-ATPase activity subjected to denervation surgery showed significantly reduction when compared with the sham groups (p < 0.05). A positive correlation existed between norepinephrine (NE) content and Na+-K+-ATPase activity in the kidney (r2 = 0.579). Renal Na+-K+-ATPase α1 subunit mRNA expression was down-regulated in the RDNX group compared with the sham group (P < 0.05), while renal Na+-K+-ATPase α1 subunit mRNA expression was no statistical significance between the groups (P = 0.63). Immunohistochemical analysis showed that there were significant differences in the renal expression of Na+-K+-ATPasebetween the three groups (P < 0.05). CONCLUSIONS These experiments demonstrate that RDN exerted an anti-hypertensive effect with reduction of EO levels and Na+-K+-ATPase activity and Na+-K+-ATPase α1 subunit expression of kidney in SHR.
Collapse
Affiliation(s)
- Xiaomei Lai
- Postgraduate. Guangxi Medical University – First Affiliated Hospital – Department of Cardiology – Nanning, China
| | - Hong Wen
- PhD. Guangxi Medical University – First Affiliated Hospital – Department of Cardiology – Nanning, China
| | - Tingting Yang
- Postgraduate. Guangxi Medical University – First Affiliated Hospital – Department of Cardiology – Nanning, China
| | - Fei Qin
- Postgraduate. Guangxi Medical University – First Affiliated Hospital – Department of Cardiology – Nanning, China
| | - Xiaoge Zhong
- Postgraduate. Guangxi Medical University – First Affiliated Hospital – Department of Cardiology – Nanning, China
| | - Yajin Pan
- Postgraduate. Guangxi Medical University – First Affiliated Hospital – Department of Cardiology – Nanning, China
| | - Jie Yu
- Postgraduate. Guangxi Medical University – First Affiliated Hospital – Department of Cardiology – Nanning, China
| | - Jing Huang
- Postgraduate. Guangxi Medical University – First Affiliated Hospital – Department of Cardiology – Nanning, China
| | - Jianling Li
- PhD, and Postdoctoral Mobile Station. Guangxi Medical University – First Affiliated Hospital – Department of Cardiology – Nanning, China.,Corresponding author:
- 13407710624
| |
Collapse
|
2
|
Chen L, Zhang M, Wang X, Liu Y, Bian J, Yan D, Yin W. Cardiac steroid ouabain transcriptionally increases human leukocyte antigen DR expression on monocytes. Steroids 2021; 175:108915. [PMID: 34508735 DOI: 10.1016/j.steroids.2021.108915] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Revised: 07/31/2021] [Accepted: 08/30/2021] [Indexed: 01/18/2023]
Abstract
Sepsis is a life-threatening disease characterized by acute multiple organ dysfunction and immunosuppression that is also called as immunoparalysis. Increasing evidence suggests that immunoparalysis largely contributes to the high mortality of sepsis, but the effective remedies are lacking. As an important antigen presentation molecule, human leukocyte antigen DR (HLA-DR) is remarkably down-regulated in sepsis-induced immunoparalysis, therefore, re-stimulation of HLA-DR expression is expected to be useful in reversing immunoparalysis. We previously described that ouabain, as a Na+, K+-ATPase ligand, is able to counteract immunoparalysis by regulating TH1 cytokines expression. Here, we expanded the finding that ouabain not only prevents LPS-induced down-regulation of HLA-DR on monocytes, but also transcriptionally activates HLA-DR α/β expression mediated by CIITA4, IRF1, c-Src, and Stat1 phosphorylation. Since ouabain can improve sepsis-induced immunoparalysis by multiple mechanisms, we propose that ouabain may be a promising agent in septic therapy that deserves further investigation.
Collapse
Affiliation(s)
- Lili Chen
- State Key Lab of Pharmaceutical Biotechnology, College of Life Sciences, Nanjing University, Nanjing, China
| | - Manli Zhang
- State Key Lab of Pharmaceutical Biotechnology, College of Life Sciences, Nanjing University, Nanjing, China
| | - Xiya Wang
- State Key Lab of Pharmaceutical Biotechnology, College of Life Sciences, Nanjing University, Nanjing, China
| | - Yongjian Liu
- State Key Lab of Pharmaceutical Biotechnology, College of Life Sciences, Nanjing University, Nanjing, China
| | - Jinjun Bian
- Department of Anesthesiology and Critical Care, Changhai Hospital, Naval Medical University, Shanghai, China.
| | - Dong Yan
- Affiliated Hospital of Nanjing University of Chinese Medicine, Jiangsu Province Hospital of Chinese Medicine, China.
| | - Wu Yin
- State Key Lab of Pharmaceutical Biotechnology, College of Life Sciences, Nanjing University, Nanjing, China.
| |
Collapse
|
3
|
Marck PV, Pessoa MT, Xu Y, Kutz LC, Collins DM, Yan Y, King C, Wang X, Duan Q, Cai L, Xie JX, Lingrel JB, Xie Z, Tian J, Pierre SV. Cardiac Oxidative Signaling and Physiological Hypertrophy in the Na/K-ATPase α1 s/sα2 s/s Mouse Model of High Affinity for Cardiotonic Steroids. Int J Mol Sci 2021; 22:ijms22073462. [PMID: 33801629 PMCID: PMC8036649 DOI: 10.3390/ijms22073462] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2021] [Revised: 03/18/2021] [Accepted: 03/23/2021] [Indexed: 11/25/2022] Open
Abstract
The Na/K-ATPase is the specific receptor for cardiotonic steroids (CTS) such as ouabain and digoxin. At pharmacological concentrations used in the treatment of cardiac conditions, CTS inhibit the ion-pumping function of Na/K-ATPase. At much lower concentrations, in the range of those reported for endogenous CTS in the blood, they stimulate hypertrophic growth of cultured cardiac myocytes through initiation of a Na/K-ATPase-mediated and reactive oxygen species (ROS)-dependent signaling. To examine a possible effect of endogenous concentrations of CTS on cardiac structure and function in vivo, we compared mice expressing the naturally resistant Na/K-ATPase α1 and age-matched mice genetically engineered to express a mutated Na/K-ATPase α1 with high affinity for CTS. In this model, total cardiac Na/K-ATPase activity, α1, α2, and β1 protein content remained unchanged, and the cardiac Na/K-ATPase dose–response curve to ouabain shifted to the left as expected. In males aged 3–6 months, increased α1 sensitivity to CTS resulted in a significant increase in cardiac carbonylated protein content, suggesting that ROS production was elevated. A moderate but significant increase of about 15% of the heart-weight-to-tibia-length ratio accompanied by an increase in the myocyte cross-sectional area was detected. Echocardiographic analyses did not reveal any change in cardiac function, and there was no fibrosis or re-expression of the fetal gene program. RNA sequencing analysis indicated that pathways related to energy metabolism were upregulated, while those related to extracellular matrix organization were downregulated. Consistent with a functional role of the latter, an angiotensin-II challenge that triggered fibrosis in the α1r/rα2s/s mouse failed to do so in the α1s/sα2s/s. Taken together, these results are indicative of a link between circulating CTS, Na/K-ATPase α1, ROS, and physiological cardiac hypertrophy in mice under baseline laboratory conditions.
Collapse
Affiliation(s)
- Pauline V. Marck
- Marshall Institute for Interdisciplinary Research, Huntington, WV 25703, USA; (P.V.M.); (M.T.P.); (Y.X.); (L.C.K.); (D.M.C.); (C.K.); (X.W.); (L.C.); (Z.X.); (J.T.)
| | - Marco T. Pessoa
- Marshall Institute for Interdisciplinary Research, Huntington, WV 25703, USA; (P.V.M.); (M.T.P.); (Y.X.); (L.C.K.); (D.M.C.); (C.K.); (X.W.); (L.C.); (Z.X.); (J.T.)
| | - Yunhui Xu
- Marshall Institute for Interdisciplinary Research, Huntington, WV 25703, USA; (P.V.M.); (M.T.P.); (Y.X.); (L.C.K.); (D.M.C.); (C.K.); (X.W.); (L.C.); (Z.X.); (J.T.)
| | - Laura C. Kutz
- Marshall Institute for Interdisciplinary Research, Huntington, WV 25703, USA; (P.V.M.); (M.T.P.); (Y.X.); (L.C.K.); (D.M.C.); (C.K.); (X.W.); (L.C.); (Z.X.); (J.T.)
| | - Dominic M. Collins
- Marshall Institute for Interdisciplinary Research, Huntington, WV 25703, USA; (P.V.M.); (M.T.P.); (Y.X.); (L.C.K.); (D.M.C.); (C.K.); (X.W.); (L.C.); (Z.X.); (J.T.)
| | - Yanling Yan
- Department of Biomedical Sciences, Marshall University Joan C. Edwards School of Medicine, Huntington, WV 25755, USA;
| | - Cierra King
- Marshall Institute for Interdisciplinary Research, Huntington, WV 25703, USA; (P.V.M.); (M.T.P.); (Y.X.); (L.C.K.); (D.M.C.); (C.K.); (X.W.); (L.C.); (Z.X.); (J.T.)
| | - Xiaoliang Wang
- Marshall Institute for Interdisciplinary Research, Huntington, WV 25703, USA; (P.V.M.); (M.T.P.); (Y.X.); (L.C.K.); (D.M.C.); (C.K.); (X.W.); (L.C.); (Z.X.); (J.T.)
| | - Qiming Duan
- Gladstone Institute of Cardiovascular Disease, San Francisco, CA 94158, USA;
| | - Liquan Cai
- Marshall Institute for Interdisciplinary Research, Huntington, WV 25703, USA; (P.V.M.); (M.T.P.); (Y.X.); (L.C.K.); (D.M.C.); (C.K.); (X.W.); (L.C.); (Z.X.); (J.T.)
| | - Jeffrey X. Xie
- Department of Internal Medicine, University of Michigan, Ann Arbor, MI 48109, USA;
| | - Jerry B. Lingrel
- Department of Molecular Genetics, Biochemistry and Microbiology, University of Cincinnati College of Medicine, Cincinnati, OH 45267, USA;
| | - Zijian Xie
- Marshall Institute for Interdisciplinary Research, Huntington, WV 25703, USA; (P.V.M.); (M.T.P.); (Y.X.); (L.C.K.); (D.M.C.); (C.K.); (X.W.); (L.C.); (Z.X.); (J.T.)
| | - Jiang Tian
- Marshall Institute for Interdisciplinary Research, Huntington, WV 25703, USA; (P.V.M.); (M.T.P.); (Y.X.); (L.C.K.); (D.M.C.); (C.K.); (X.W.); (L.C.); (Z.X.); (J.T.)
| | - Sandrine V. Pierre
- Marshall Institute for Interdisciplinary Research, Huntington, WV 25703, USA; (P.V.M.); (M.T.P.); (Y.X.); (L.C.K.); (D.M.C.); (C.K.); (X.W.); (L.C.); (Z.X.); (J.T.)
- Correspondence: ; Tel.: +1-(304)-696-3505
| |
Collapse
|
4
|
Features of GABAergic Cardiovascular Control Provided by Medullary Neurons in Rats. NEUROPHYSIOLOGY+ 2013. [DOI: 10.1007/s11062-013-9386-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
|
5
|
Lin NH, Chung TY, Li FY, Chen HA, Tzen JTC. Enhancing the potency of lithospermate B for inhibiting Na+/K+-ATPase activity by forming transition metal ion complexes. Acta Pharmacol Sin 2013; 34:893-900. [PMID: 23685954 DOI: 10.1038/aps.2013.32] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2012] [Accepted: 03/11/2013] [Indexed: 02/03/2023] Open
Abstract
AIM To determine whether replacing Mg(2+) in magnesium lithospermate B (Mg-LSB) isolated from danshen (Salvia miltiorrhiza) with other metal ions could affect its potency in inhibition of Na(+)/K(+)-ATPase activity. METHODS Eight metal ions (Na(+), K(+), Mg(2+), Cr(3+), Mn(2+), Co(2+), Ni(2+), and Zn(2+)) were used to form complexes with LSB. The activity of Na(+)/K(+)-ATPase was determined by measuring the amount of inorganic phosphate (Pi) liberated from ATP. Human adrenergic neuroblastoma cell line SH-SY5Y was used to assess the intracellular Ca(2+) level fluctuation and cell viability. The metal binding site on LSB and the binding mode of the metal-LSB complexes were detected by NMR and visible spectroscopy, respectively. RESULTS The potencies of LSB complexed with Cr(3+), Mn(2+), Co(2+), or Ni(2+) increased by approximately 5 times compared to the naturally occurring LSB and Mg-LSB. The IC50 values of Cr-LSB, Mn-LSB, Co-LSB, Ni-LSB, LSB, and Mg-LSB in inhibition of Na(+)/K(+)-ATPase activity were 23, 17, 26, 25, 101, and 128 μmol/L, respectively. After treatment of SH-SY5Y cells with the transition metal-LSB complexes (25 μmol/L), the intracellular Ca(2+) level was substantially elevated, and the cells were viable for one day. The transition metals, as exemplified by Co(2+), appeared to be coordinated by two carboxylate groups and one carbonyl group of LSB. Titration of LSB against Co(2+) demonstrated that the Co-LSB complex was formed with a Co(2+):LSB molar ratio of 1:2 or 1:1, when [Co(2+)] was less than half of the [LSB] or higher than the [LSB], respectively. CONCLUSION LSB complexed with Cr(3+), Mn(2+), Co(2+), or Ni(2+) are stable, non-toxic and more potent in inhibition of Na(+)/K(+)-ATPase. The transition metal-LSB complexes have the potential to be superior substitutes for cardiac glycosides in the treatment of congestive heart failure.
Collapse
|
6
|
Blanco G, Wallace DP. Novel role of ouabain as a cystogenic factor in autosomal dominant polycystic kidney disease. Am J Physiol Renal Physiol 2013; 305:F797-812. [PMID: 23761677 DOI: 10.1152/ajprenal.00248.2013] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
The classic role of the Na-K-ATPase is that of a primary active transporter that utilizes cell energy to establish and maintain transmembrane Na(+) and K(+) gradients to preserve cell osmotic stability, support cell excitability, and drive secondary active transport. Recent studies have revealed that Na-K-ATPase located within cholesterol-containing lipid rafts serves as a receptor for cardiotonic steroids, including ouabain. Traditionally, ouabain was viewed as a toxin produced only in plants, and it was used in relatively high concentrations to experimentally block the pumping action of the Na-K-ATPase. However, the new and unexpected role of the Na-K-ATPase as a signal transducer revealed a novel facet for ouabain in the regulation of a myriad of cell functions, including cell proliferation, hypertrophy, apoptosis, mobility, and metabolism. The seminal discovery that ouabain is endogenously produced in mammals and circulates in plasma has fueled the interest in this endogenous molecule as a potentially important hormone in normal physiology and disease. In this article, we review the role of the Na-K-ATPase as an ion transporter in the kidney, the experimental evidence for ouabain as a circulating hormone, the function of the Na-K-ATPase as a signal transducer that mediates ouabain's effects, and novel results for ouabain-induced Na-K-ATPase signaling in cystogenesis of autosomal dominant polycystic kidney disease.
Collapse
Affiliation(s)
- Gustavo Blanco
- Dept. of Molecular and Integrative Physiology, 3901 Rainbow Blvd., Kansas City, KS 66160.
| | | |
Collapse
|
7
|
Takahashi H, Yoshika M, Komiyama Y, Nishimura M. The central mechanism underlying hypertension: a review of the roles of sodium ions, epithelial sodium channels, the renin-angiotensin-aldosterone system, oxidative stress and endogenous digitalis in the brain. Hypertens Res 2011; 34:1147-60. [PMID: 21814209 PMCID: PMC3324327 DOI: 10.1038/hr.2011.105] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2011] [Revised: 05/08/2011] [Accepted: 05/15/2011] [Indexed: 02/07/2023]
Abstract
The central nervous system has a key role in regulating the circulatory system by modulating the sympathetic and parasympathetic nervous systems, pituitary hormone release, and the baroreceptor reflex. Digoxin- and ouabain-like immunoreactive materials were found >20 years ago in the hypothalamic nuclei. These factors appeared to localize to the paraventricular and supraoptic nuclei and the nerve fibers at the circumventricular organs and supposed to affect electrolyte balance and blood pressure. The turnover rate of these materials increases with increasing sodium intake. As intracerebroventricular injection of ouabain increases blood pressure via sympathetic activation, an endogenous digitalis-like factor (EDLF) was thought to regulate cardiovascular system-related functions in the brain, particularly after sodium loading. Experiments conducted mainly in rats revealed that the mechanism of action of ouabain in the brain involves sodium ions, epithelial sodium channels (ENaCs) and the renin-angiotensin-aldosterone system (RAAS), all of which are affected by sodium loading. Rats fed a high-sodium diet develop elevated sodium levels in their cerebrospinal fluid, which activates ENaCs. Activated ENaCs and/or increased intracellular sodium in neurons activate the RAAS; this releases EDLF in the brain, activating the sympathetic nervous system. The RAAS promotes oxidative stress in the brain, further activating the RAAS and augmenting sympathetic outflow. Angiotensin II and aldosterone of peripheral origin act in the brain to activate this cascade, increasing sympathetic outflow and leading to hypertension. Thus, the brain Na(+)-ENaC-RAAS-EDLF axis activates sympathetic outflow and has a crucial role in essential and secondary hypertension. This report provides an overview of the central mechanism underlying hypertension and discusses the use of antihypertensive agents.
Collapse
Affiliation(s)
- Hakuo Takahashi
- Department of Clinical Sciences and Laboratory Medicine, Kansai Medical University, Hirakata City, Osaka, Japan.
| | | | | | | |
Collapse
|
8
|
Active ingredients in Chinese medicines promoting blood circulation as Na+/K+ -ATPase inhibitors. Acta Pharmacol Sin 2011; 32:141-51. [PMID: 21293466 DOI: 10.1038/aps.2010.197] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The positive inotropic effect of cardiac glycosides lies in their reversible inhibition on the membrane-bound Na(+)/K(+)-ATPase in human myocardium. Steroid-like compounds containing a core structure similar to cardiac glycosides are found in many Chinese medicines conventionally used for promoting blood circulation. Some of them are demonstrated to be Na(+)/K(+)-ATPase inhibitors and thus putatively responsible for their therapeutic effects via the same molecular mechanism as cardiac glycosides. On the other hand, magnesium lithospermate B of danshen is also proposed to exert its cardiac therapeutic effect by effectively inhibiting Na(+)/K(+)-ATPase. Theoretical modeling suggests that the number of hydrogen bonds and the strength of hydrophobic interaction between the effective ingredients of various medicines and residues around the binding pocket of Na(+)/K(+)-ATPase are crucial for the inhibitory potency of these active ingredients. Ginsenosides, the active ingredients in ginseng and sanqi, substantially inhibit Na(+)/K(+)-ATPase when sugar moieties are attached only to the C-3 position of their steroid-like structure, equivalent to the sugar position in cardiac glycosides. Their inhibitory potency is abolished, however, when sugar moieties are linked to C-6 or C-20 position of the steroid nucleus; presumably, these sugar attachments lead to steric hindrance for the entrance of ginsenosides into the binding pocket of Na(+)/K(+)-ATPase. Neuroprotective effects of cardiac glycosides, several steroid-like compounds, and magnesium lithospermate B against ischemic stroke have been accordingly observed in a cortical brain slice-based assay model, and cumulative data support that effective inhibitors of Na(+)/K(+)-ATPase in the brain could be potential drugs for the treatment of ischemic stroke.
Collapse
|
9
|
Touza NA, Pôças ESC, Quintas LEM, Cunha-Filho G, Santos ML, Noël F. Inhibitory effect of combinations of digoxin and endogenous cardiotonic steroids on Na+/K+-ATPase activity in human kidney membrane preparation. Life Sci 2011; 88:39-42. [DOI: 10.1016/j.lfs.2010.10.027] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2010] [Revised: 09/22/2010] [Accepted: 10/19/2010] [Indexed: 09/30/2022]
|
10
|
Holthouser KA, Mandal A, Merchant ML, Schelling JR, Delamere NA, Valdes RR, Tyagi SC, Lederer ED, Khundmiri SJ. Ouabain stimulates Na-K-ATPase through a sodium/hydrogen exchanger-1 (NHE-1)-dependent mechanism in human kidney proximal tubule cells. Am J Physiol Renal Physiol 2010; 299:F77-90. [PMID: 20427472 DOI: 10.1152/ajprenal.00581.2009] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Recent investigations demonstrate increased Na/H exchanger-1 (NHE-1) activity and plasma levels of ouabain-like factor in spontaneously hypertensive rats. At nanomolar concentrations, ouabain increases Na-K-ATPase activity, induces cell proliferation, and activates complex signaling cascades. We hypothesize that the activity of NHE-1 and Na-K-ATPase are interdependent. To test whether treatment with picomolar ouabain regulates Na-K-ATPase through an NHE-1-dependent mechanism, we examined the role of NHE-1 in ouabain-mediated stimulation of Na-K-ATPase in kidney proximal tubule cell lines [opossum kidney (OK), HK-2, HKC-5, and HKC-11] and rat kidney basolateral membranes. Ouabain stimulated Na-K-ATPase activity and tyrosine phosphorylation in cells that express NHE-1 (OK, HKC-5, and HKC-11) but not in HK-2 cells that express very low levels of NHE-1. Inhibition of NHE-1 with 5 microM EIPA, a NHE-1-specific inhibitor, prevented ouabain-mediated stimulation of (86)Rb uptake and Na-K-ATPase phosphorylation in OK, HKC-5, and HKC-11 cells. Expression of wild-type NHE-1 in HK2 cells restored regulation of Na-K-ATPase by picomolar ouabain. Treatment with picomolar ouabain increased membrane expression of Na-K-ATPase and enhanced NHE-1-Na-K-ATPase alpha1-subunit association. Treatment with ouabain (1 microg x kg body wt(-1) x day(-1)) increased Na-K-ATPase activity, expression, phosphorylation, and association with NHE-1 increased in rat kidney cortical basolateral membranes. Eight days' treatment with ouabain (1 microg x kg body wt(-1) x day(-1)) resulted in increased blood pressure in these rats. These results suggest that the association of NHE-1 with Na-K-ATPase is critical for ouabain-mediated regulation of Na-K-ATPase and that these effects may play a role in cardioglycoside-stimulated hypertension.
Collapse
Affiliation(s)
- Kristine A Holthouser
- Department of Medicine/Kidney Disease Program, University of Louisville, Louisville, Kentucky, USA
| | | | | | | | | | | | | | | | | |
Collapse
|
11
|
Zhang YR, Yuan ZY. Dopamine-mediated inhibition of renal Na+/K+-ATPase in HK-2 cells is reduced by ouabain. Clin Exp Pharmacol Physiol 2010; 37:613-8. [PMID: 20132239 DOI: 10.1111/j.1440-1681.2010.05364.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
1. Abnormal renal sodium handling is considered a major contributing factor in hypertension associated with chronic ouabain treatment. However, the molecular mechanisms involved in abnormal renal sodium handling have not been elucidated. Therefore, we investigated whether chronic ouabain treatment perturbs dopamine D(1) receptor function. 2. The expression and phosphorylation levels of the D(1) receptor in cells of the human proximal tubule cell line (HK-2) were determined using western blot analysis and reverse transcription polymerase chain reaction. The activity of the renal sodium/potassium pump (Na(+)/K(+)-ATPase) was measured using a colourimetric assay, and cyclic adenosine monophosphate accumulation was determined by performing a radioimmunoassay. 3. We showed that chronic ouabain treatment decreased the protein and mRNA expression levels of the D(1) receptor and increased the basal phosphorylation of the D(1) receptor in HK-2 cells. We also showed that in the presence of ouabain, HK-2 cells did not reveal the cyclic adenosine monophosphate accumulation and Na(+)/K(+)-ATPase inhibition induced by the D(1) receptor agonist fenoldopam. 4. We hypothesize that the ouabain-induced decrease in renal D(1) receptor function is responsible for the increase in renal sodium reabsorption, which eventually leads to ouabain-induced hypertension.
Collapse
Affiliation(s)
- Yu-Rong Zhang
- Department of Cardiovascular Medicine, First Affiliated Hospital of Medical School, Xi'an Jiaotong University, Xi'an, Shaanxi 710061, China
| | | |
Collapse
|
12
|
Effects of long-term ouabain treatment on blood pressure, sodium excretion, and renal dopamine D1 receptor levels in rats. J Comp Physiol B 2009; 180:117-24. [DOI: 10.1007/s00360-009-0391-z] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2009] [Revised: 06/25/2009] [Accepted: 06/29/2009] [Indexed: 01/11/2023]
|
13
|
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: 384] [Impact Index Per Article: 25.6] [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.
Collapse
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.
| | | | | |
Collapse
|
14
|
Bagrov AY, Shapiro JI. Endogenous digitalis: pathophysiologic roles and therapeutic applications. NATURE CLINICAL PRACTICE. NEPHROLOGY 2008; 4:378-92. [PMID: 18542120 PMCID: PMC2574729 DOI: 10.1038/ncpneph0848] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2008] [Accepted: 04/29/2008] [Indexed: 12/22/2022]
Abstract
Endogenous digitalis-like factors, also called cardiotonic steroids, have been thought for nearly half a century to have important roles in health and disease. The endogenous cardiotonic steroids ouabain and marinobufagenin have been identified in humans, and an effector mechanism has been delineated by which these hormones signal through the sodium/potassium-transporting ATPase. These findings have increased interest in this field substantially. Although cardiotonic steroids were first considered important in the regulation of renal sodium transport and arterial pressure, subsequent work has implicated these hormones in the control of cell growth, apoptosis and fibrosis, among other processes. This Review focuses on the role of endogenous cardiotonic steroids in the pathophysiology of essential hypertension, congestive heart failure, end-stage renal disease and pre-eclampsia. We also discuss potential therapeutic strategies that have emerged as a result of the increased understanding of the regulation and actions of cardiotonic steroids.
Collapse
Affiliation(s)
- Alexei Y Bagrov
- Hypertension Unit at Laboratory of Cardiovascular Science, Intramural Research Program, National Institute on Aging, NIH, Baltimore 21224, MD, USA.
| | | |
Collapse
|
15
|
Abstract
Cardiac glycosides have been used for decades to treat congestive heart failure. The recent identification of cardiotonic steroids such as ouabain, digoxin, marinobufagenin, and telocinobufagin in blood plasma, adrenal glands, and hypothalamus of mammals led to exciting new perspectives in the pathology of heart failure and arterial hypertension. Biosynthesis of ouabain and digoxin occurs in adrenal glands and is under the control of angiotensin II, endothelin, and epinephrine released from cells of the midbrain upon stimulation of brain areas sensing cerebrospinal Na(+) concentration and, apparently, the body's K(+) content. Rapid changes of endogenous ouabain upon physical exercise may favor the economy of the heart by a rise of intracellular Ca(2)(+) levels in cardiac and atrial muscle cells. According to the sodium pump lag hypothesis, this may be accomplished by partial inhibition of the sodium pump and Ca(2+) influx via the Na(+)/Ca(2+) exchanger working in reverse mode or via activation of the Na(+)/K(+)-ATPase signalosome complex, generating intracellular calcium oscillations, reactive oxygen species, and gene activation via nuclear factor-kappaB or extracellular signal-regulated kinases 1 and 2. Elevated concentrations of endogenous ouabain and marinobufagenin in the subnanomolar concentration range were found to stimulate proliferation and differentiation of cardiac and smooth muscle cells. They may have a primary role in the development of cardiac dysfunction and failure because (i) offspring of hypertensive patients evidently inherit elevated plasma concentrations of endogenous ouabain; (ii) such elevated concentrations correlate positively with cardiac dysfunction, hypertrophy, and arterial hypertension; (iii) about 40% of Europeans with uncomplicated essential hypertension show increased concentrations of endogenous ouabain associated with reduced heart rate and cardiac hypertrophy; (iv) in patients with advanced arterial hypertension, circulating levels of endogenous ouabain correlate with BP and total peripheral resistance; (v) among patients with idiopathic dilated cardiomyopathy, high circulating levels of endogenous ouabain and marinobufagenin identify those individuals who are predisposed to progressing more rapidly to heart failure, suggesting that endogenous ouabain (and marinobufagenin) may contribute to toxicity upon digoxin therapy. In contrast to endogenous ouabain, endogenous marinobufagenin may act as a natriuretic substance as well. It shows a higher affinity for the ouabain-insensitive alpha(1) isoform of Na(+)/K(+)-ATPase of rat kidney tubular cells and its levels are increased in volume expansion and pre-eclampsia. Digoxin, which is synthesized in adrenal glands, seems to counteract the hypertensinogenic action of ouabain in rats, as do antibodies against ouabain, for example, (Digibind) and rostafuroxin (PST 2238), a selective ouabain antagonist. It lowers BP in ouabain- and adducin-dependent hypertension in rats and is a promising new class of antihypertensive medication in humans.
Collapse
Affiliation(s)
- Wilhelm Schoner
- Institute of Biochemistry and Endocrinology, Justus-Liebig-University Giessen, Giessen, Germany.
| | | |
Collapse
|
16
|
|
17
|
Kikkawa K. [Antihypertensive drugs in clinical development]. Nihon Yakurigaku Zasshi 2006; 127:381-6. [PMID: 16819244 DOI: 10.1254/fpj.127.381] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
|