1
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Patni N, Fatima M, Lamis A, Siddiqui SW, Ashok T, Muhammad A. Magnesium and Hypertension: Decoding Novel Anti-hypertensives. Cureus 2022; 14:e25839. [PMID: 35836446 PMCID: PMC9273175 DOI: 10.7759/cureus.25839] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/09/2022] [Indexed: 11/26/2022] Open
Abstract
Hypertension (HTN) is a complex multifactorial disease that is one of the most prevalent disorders in our modern world. It can lead to fatal complications like coronary artery disease (CAD) and congestive heart failure (CHF) in high-risk individuals. The silent nature of HTN also contributes to its immense caseload and, today, with a number of combinations and various antihypertensive agents, patient compliance is becoming increasingly difficult. This article has reviewed the role and mechanisms of magnesium (Mg) in reducing HTN in the human body so as to provide more information that may help include it as a mainstream antihypertensive regimen. This review has also shed light on the cardioprotective nature of Mg against pathologies like CHF with special mention to patient groups who are at high risk for low Mg levels. Many studies included in this article solidify the former link, but some also provide contradicting data.
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2
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Odom MJ, Zuckerman SL, Mocco J. The role of magnesium in the management of cerebral vasospasm. Neurol Res Int 2013; 2013:943914. [PMID: 23766903 PMCID: PMC3674682 DOI: 10.1155/2013/943914] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2012] [Revised: 04/29/2013] [Accepted: 05/01/2013] [Indexed: 11/17/2022] Open
Abstract
Subarachnoid hemorrhage (SAH) is characterized by bleeding into the subarachnoid space, often caused by ruptured aneurysm. Aneurysmal rupture occurs in 700,000 individuals per year worldwide, with 40,000 cases taking place in the United States. Beyond the high mortality associated with SAH alone, morbidity and mortality are further increased with the occurrence of cerebral vasospasm, a pathologic constriction of blood vessels that can lead to delayed ischemic neurologic deficits (DIND). Treatment of cerebral vasospasm is a source of contention. One extensively studied therapy is Magnesium (Mg) as both a competitive antagonist of calcium at the N-methyl D-aspartate (NMDA) receptor, and a noncompetitive antagonist of both IP3 and voltage-gated calcium channels, leading to smooth muscle relaxation. In our literature review, several animal and human studies are summarized in addition to two Phase III trials assessing the use of intravenous Mg in the treatment of SAH (IMASH and MASH-2). Though many studies have shown promise for the use of Mg in SAH, there has been inconsistency in study design and outcomes. Furthermore, the results of the recently completed clinical trials have shown no significant benefit from using intravenous Mg as adjuvant therapy in the treatment of cerebral vasospasm.
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Affiliation(s)
- Mitchell J. Odom
- Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - Scott L. Zuckerman
- Department of Neurological Surgery, Vanderbilt University School of Medicine, 1211 Medical Center Drive, Nashville, TN 37232, USA
| | - J Mocco
- Department of Neurological Surgery, Vanderbilt University School of Medicine, 1211 Medical Center Drive, Nashville, TN 37232, USA
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3
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Vasomotor response induced by change of extracellular potassium and magnesium in cerebral penetrating arterioles. Neurosci Res 2011; 70:30-4. [DOI: 10.1016/j.neures.2011.01.017] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2010] [Revised: 01/10/2011] [Accepted: 01/25/2011] [Indexed: 11/18/2022]
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4
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Zheng T, Li W, Altura BT, Shah NC, Altura BM. Sphingolipids regulate [Mg2+]o uptake and [Mg2+]i content in vascular smooth muscle cells: potential mechanisms and importance to membrane transport of Mg2+. Am J Physiol Heart Circ Physiol 2010; 300:H486-92. [PMID: 21112948 DOI: 10.1152/ajpheart.00976.2010] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Sphingolipids have a variety of important signaling roles in mammalian cells. We tested the hypothesis that certain sphingolipids and neutral sphingomyelinase (N-SMase) can regulate intracellular free magnesium ions ([Mg2+]i) in vascular smooth muscle (VSM) cells. Herein, we show that several sphingolipids, including C2-ceramide, C8-ceramide, C16-ceramide, and sphingosine, as well as N-SMase, have potent and direct effects on content and mobilization of [Mg2+]i in primary cultured rat aortic smooth muscle cells. All of these sphingolipid molecules increase, rapidly, [Mg2+]i in these vascular cells in a concentration-dependent manner. The increments of [Mg2+]i, induced by these agents, are derived from influx of extracellular Mg2+ and are extracellular Ca2+ concentration-dependent. Phospholipase C and Ca2+/calmodulin/Ca2+-ATPase activity appear to be important in the sphingolipid-induced rises of [Mg2+]i. Activation of certain PKC isozymes may also be required for sphingolipid-induced rises in [Mg2+]i. These novel results suggest that sphingolipids may be homeostatic regulators of extracellular Mg2+ concentration influx (and transport) and [Mg2+]i content in vascular muscle cells.
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Affiliation(s)
- Tao Zheng
- Department of Physiology and Pharmacology, Center For Cardiovascular and Muscle Research, The School of Graduate Studies Program in Molecular and Cellular Science, State University of New York, Box 31, SUNY Health Science Center at Brooklyn, 450 Clarkson Ave., Brooklyn, NY 11203, USA
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5
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Mubagwa K, Gwanyanya A, Zakharov S, Macianskiene R. Regulation of cation channels in cardiac and smooth muscle cells by intracellular magnesium. Arch Biochem Biophys 2007; 458:73-89. [PMID: 17123458 DOI: 10.1016/j.abb.2006.10.014] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2006] [Revised: 10/16/2006] [Accepted: 10/16/2006] [Indexed: 01/06/2023]
Abstract
Magnesium regulates various ion channels in many tissues, including those of the cardiovascular system. General mechanisms by which intracellular Mg(2+) (Mg(i)(2+)) regulates channels are presented. These involve either a direct interaction with the channel, or an indirect modification of channel function via other proteins, such as enzymes or G proteins, or via membrane surface charges and phospholipids. To provide an insight into the role of Mg(i)(2+) in the cardiovascular system, effects of Mg(i)(2+) on major channels in cardiac and smooth muscle cells and the underlying mechanisms are then reviewed. Although Mg(i)(2+) concentrations are known to be stable, conditions under which they may change exist, such as following stimulation of beta-adrenergic receptors and of insulin receptors, or during pathophysiological conditions such as ischemia, heart failure or hypertension. Modifications of cardiovascular electrical or mechanical function, possibly resulting in arrhythmias or hypertension, may result from such changes of Mg(i)(2+) and their effects on cation channels.
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Affiliation(s)
- Kanigula Mubagwa
- Division of Experimental Cardiac Surgery, Department of Heart and Vessel Diseases, Katholieke Universiteit Leuven, Campus Gasthuisberg, Herestraat 49, B-3000 Leuven, Belgium.
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6
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Yang Y, Wu Z, Chen Y, Qiao J, Gao M, Yuan J, Nie W, Guo Y. Magnesium Deficiency Enhances Hydrogen Peroxide Production and Oxidative Damage in Chick Embryo Hepatocyte In Vitro. Biometals 2006; 19:71-81. [PMID: 16502333 DOI: 10.1007/s10534-005-6898-1] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2005] [Accepted: 05/04/2005] [Indexed: 10/25/2022]
Abstract
Magnesium deficiency and oxidative stress have been identified as correlative factors in many diseases. The origin of free radicals correlated with oxidative damage resulting from Mg-deficiency is unclear at the cellular level. To investigate whether hydrogen peroxide (H2O2) is associated in the oxidative stress induced by Mg-deficiency, the effect of Mg2+ deficiency (0, 0.4, 0.7 mM) on the metabolism of H2O2 was investigated in cultured chick embryo hepatocytes. After being cultured in the media with various concentrations of Mg2+ for 1, 2, 4, 6 and 10 days, parameters of H2O2 production, catalase activity, lipid peroxidation, intracellular total Mg and cell viability were analyzed. Results demonstrated that long-term incubation of chick embryo hepatocyte in extracellular Mg2+-deprivative and Mg2+-deficient (0.4 mM) states significantly enhanced the production of H2O2 (approximately twofold, respectively) and lipid peroxidation in the cell cultures, while decreasing the cell viability. Additionally, the reversing action of Mg2+ re-added to 1.0 mM and the partial reversing action of dimethylthiourea suggested that (i) [Mg2+]e deficiency induced the increase of H2O2 production, (ii) [Mg2+]e deficiency decreased catalase activity in chick embryo hepatocyte in vitro, subsequently causing oxidative stress and cell peroxidative damage.
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Affiliation(s)
- Ying Yang
- Division of Animal Nutrition and Feed Science, College of Animal Science and Technology, China Agricultural University (CAU), Beijing, 100094, P.R. China
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7
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Touyz RM, He Y, Montezano ACI, Yao G, Chubanov V, Gudermann T, Callera GE. Differential regulation of transient receptor potential melastatin 6 and 7 cation channels by ANG II in vascular smooth muscle cells from spontaneously hypertensive rats. Am J Physiol Regul Integr Comp Physiol 2006; 290:R73-8. [PMID: 16109804 DOI: 10.1152/ajpregu.00515.2005] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Intracellular Mg2+ depletion has been implicated in vascular dysfunction in hypertension. We demonstrated that transient receptor potential melastatin 7 (TRPM7) cation channels mediate Mg2+ influx in VSMCs. Whether this plays a role in [Mg2+]i deficiency in hypertension is unclear. Here, we tested the hypothesis that downregulation of TRPM7 and its homologue TRPM6 is associated with reduced [Mg2+]i and that ANG II negatively regulates TRPM6/7 in vascular smooth muscle cells (VSMCs) from spontaneously hypertensive rats (SHR). Cultured VSMCs from Wistar Kyoto (WKY) and SHR were studied. mRNA and protein expression of TRPM6 and TRPM7 were assessed by RT-PCR and immunoblotting, respectively. Translocation of annexin-1, specific TRPM7 substrate, was measured as an index of TRPM7 activation. [Mg2+]i was determined using mag fura-2. VSMCs from WKY and SHR express TRPM6 and TRPM7. Basal TRPM6 expression was similar in WKY and SHR, but basal TRPM7 content was lower in VSMCs from SHR vs. WKY. This was associated with significantly reduced [Mg2+]i in SHR cells ( P < 0.01). ANG II time-dependently increased TRPM6 expression, with similar responses in WKY and SHR. ANG II significantly increased TRPM7 expression in WKY ( P < 0.05), but not in SHR. Annexin-1 translocation was reduced 1.5–2-fold in SHR vs. WKY. Our findings demonstrate that TRPM6 and TRPM7 are differentially regulated in VSMCs from SHR and WKY. Whereas TRPM6 is unaltered in SHR, expression of TRPM7 is blunted. This was associated with attenuated annexin-1 translocation and decreased VSMC [Mg2+]i in SHR. Downregulation of TRPM7, but not TRPM6, may play a role in altered Mg2+ homeostasis in VSMCs from SHR.
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Affiliation(s)
- Rhian M Touyz
- Kidney Research Centre, University of Ottawa, Rm. 1333A, 451 Smyth Road, K1H 8M5, Ottawa, ON.
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8
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He Y, Yao G, Savoia C, Touyz RM. Transient Receptor Potential Melastatin 7 Ion Channels Regulate Magnesium Homeostasis in Vascular Smooth Muscle Cells. Circ Res 2005; 96:207-15. [PMID: 15591230 DOI: 10.1161/01.res.0000152967.88472.3e] [Citation(s) in RCA: 155] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Magnesium modulates vascular smooth muscle cell (VSMC) function. However, molecular mechanisms regulating VSMC Mg
2+
remain unknown. Using biochemical, pharmacological, and genetic tools, the role of transient receptor potential membrane melastatin 7 (TRPM7) cation channel in VSMC Mg
2+
homeostasis was evaluated. Rat, mouse, and human VSMCs were studied. Reverse transcriptase polymerase chain reaction and immunoblotting demonstrated TRPM7 presence in VSMCs (membrane and cytosol). Angiotensin II (Ang II) and aldosterone increased TRPM7 expression. Gene silencing using small interfering RNA (siRNA) against TRPM7, downregulated TRPM7 (mRNA and protein). Basal [Mg
2+
]
i
, measured by mag fura-2AM, was reduced in siRNA-transfected cells (0.39±0.01 mmol/L) versus controls (0.54±0.01 mmol/L;
P
<0.01). Extracellular Mg
2+
dose-dependently increased [Mg
2+
]
i
in control cells (E
max
0.70±0.02 mmol/L) and nonsilencing siRNA-transfected cells (E
max
0.71±0.04 mmol/L), but not in siRNA-transfected cells (E
max
0.5±0.01 mmol/L). The functional significance of TRPM7 was evaluated by assessing [Mg
2+
]
i
and growth responses to Ang II in TRPM7 knockdown cells. Acute Ang II stimulation decreased [Mg
2+
]
i
in control and TRPM7-deficient cells in a Na
+
-dependent manner. Chronic stimulation increased [Mg
2+
]
i
in control, but not in siRNA-transfected VSMCs. Ang II–induced DNA and protein synthesis, measured by
3
[H]-thymidine and
3
[H]-leucine incorporation, respectively, were increased in control and nonsilencing cells, but not in TRPM7 knockdown VSMCs. Our data indicate that VSMCs possess membrane-associated, Ang II–, and aldosterone-regulated TRPM7 channels, which play a role in regulating basal [Mg
2+
]
i
, transmembrane Mg
2+
transport and DNA and protein synthesis. These novel findings identify TRPM7 as a functionally important regulator of Mg
2+
homeostasis and growth in VSMCs.
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Affiliation(s)
- Ying He
- CIHR Multidisciplinary Research Group on Hypertension, Clinical Research Institute of Montreal, Canada
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9
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Northcott CA, Watts SW. Low [Mg
2+
]
e
Enhances Arterial Spontaneous Tone via Phosphatidylinositol 3-Kinase in DOCA-Salt Hypertension. Hypertension 2004; 43:125-9. [PMID: 14638620 DOI: 10.1161/01.hyp.0000103631.68328.03] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Phosphatidylinositol 3-kinase (PI3K) has been implicated in low extracellular Mg
2+
concentration ( [Mg
2+
]
e
)–induced aortic contraction, and Mg
2+
deficiency has been associated with hypertension. Moreover, arterial PI3K activity is increased in hypertensive deoxycorticosterone (DOCA)-salt rats. We hypothesized that low [Mg
2+
]
e
activates PI3K, eliciting enhanced vascular contraction, PI3K activity, and norepinephrine (NE)-induced contraction. Spontaneous tone was monitored in endothelium-denuded aortic strips from sham and DOCA-salt rats exposed to low Mg
2+
(0.15 mmol/L), high Mg
2+
(4.8 mmol/L), or normal (1.17 mmol/L) physiologic salt solution (PSS) in isolated tissue baths. LY294002 (20 μmol/L), a PI3K inhibitor, or vehicle was added (30 minutes), followed by NE (10
−9
to 3 x10
−-5
mol/L). Low [Mg
2+
]
e
significantly enhanced tone in aortas from DOCA-salt and sham rats compared with normal PSS (DOCA-salt low [Mg
2+
]
e
, +51.5 +7.0 vs DOCA-salt normal PSS, +7.1 +1.4 % of initial phenylephrine [PE] contraction). LY294002 and incubation with high Mg
2+
PSS decreased tone in aortas from DOCA-salt rats (low [Mg
2+
]
e
LY294002, −-87.5 +8.8; normal PSS LY294002, −81.7 +13.7; and high [Mg
2+
]
e
, −31.2 +10.8 % of initial PE contraction). Low [Mg
2+
]
e
leftward-shifted NE-induced aortic contractions in sham and thus matched the shift observed with DOCA (−log EC
50
mol/L: sham PSS, −7.7 +0.1; DOCA-salt PSS, −8.2 +0.1; sham low [Mg
2+
]
e
, −8.2 +0.1; and DOCA-salt low [Mg
2+
]
e
, −8.1 +0.1). Moreover, this shift was inhibited by LY294002. In conclusion, low [Mg
2+
]
e
might activate PI3K, leading to enhanced tone and agonist-induced contraction observed in aortas from DOCA-salt hypertensive rats.
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Affiliation(s)
- Carrie A Northcott
- Department of Pharmacology and To-icology, Michigan State University, B445 Life Science Bldg, East Lansing, MI 48823, USA. taetscar @msu.edu
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10
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Touyz RM, Yao G. Inhibitors of Na+/Mg2+ exchange activity attenuate the development of hypertension in angiotensin II-induced hypertensive rats. J Hypertens 2003; 21:337-44. [PMID: 12569264 DOI: 10.1097/00004872-200302000-00025] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
OBJECTIVES To investigate whether imipramine and quinidine, inhibitors of the Na /Mg exchanger, influence development of hypertension in rats infused with angiotensin (Ang) II. METHODS Sprague-Dawley rats were divided into six groups: (1) control (vehicle); (2) Ang II (150 ng/kg per min subcutaneously); (3) imipramine alone (5 mg/kg per day in drinking water); (4) quinidine alone (5 mg/kg per day in drinking water); (5) Ang II plus imipramine; (6) Ang II plus quinidine. Rats were studied for 3 weeks. To verify that Ang II directly influences Na -dependent Mg exchange, in-vitro studies were performed in vascular smooth muscle cells (VSMCs) derived from mesenteric arteries. RESULTS Ang II increased systolic blood pressure (SBP) in all groups. The magnitude of the increase was lower ( 0.01) in Ang II groups treated with imipramine (151 +/- 7.4 mmHg) or quinidine (163 +/- 4 mmHg) than in the Ang II only group (205 +/- 4 mmHg). Neither imipramine nor quinidine influenced SBP in vehicle-treated rats. Plasma concentrations of Mg and K were decreased in Ang II rats compared with controls (P < 0.05). Platelet intracellular free Mg concentration was reduced and platelet intracellular free Na concentration was increased in the Ang II group compared with control and treated groups (P < 0.01). These effects were normalized by imipramine and quinidine. Ang II stimulated Na -dependent Mg transport in VSMCs. These actions were abrogated by imipramine and quinidine and in Na -free conditions. CONCLUSIONS Our data demonstrate that inhibitors of Na -dependent Mg transport attenuate development of hypertension in rats infused with Ang II. These findings suggest a possible role for Na /Mg exchange activity in the pathogenesis of Ang II-dependent hypertension.
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Affiliation(s)
- Rhian M Touyz
- Multidisciplinary Group on Hypertension, Clinical Research Institute of Montrel, Quebec, Canada.
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11
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Yang ZW, Wang J, Zheng T, Altura BT, Altura BM. Roles of tyrosine kinase-, 1-phosphatidylinositol 3-kinase-, and mitogen-activated protein kinase-signaling pathways in ethanol-induced contractions of rat aortic smooth muscle: possible relation to alcohol-induced hypertension. Alcohol 2002; 28:17-28. [PMID: 12377357 DOI: 10.1016/s0741-8329(02)00234-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Insights into the relations between and among ethanol-induced contractions in rat aorta, tyrosine kinases (including src family of cytoplasmic tyrosine kinases), 1-phosphatidylinositol 3-kinases (PI-3Ks), mitogen-activated protein kinases (MAPKs), and regulation of intracellular free Ca(2+) ([Ca(2+)](i)) were investigated in the present study. Ethanol-induced concentration-dependent contractions in isolated rat aortic rings were attenuated greatly by pretreatment of the arteries with low concentrations of an antagonist of protein tyrosine kinases (genistein), an src homology domain 2 (SH2) inhibitor peptide, a highly specific antagonist of p38 MAPK (SB-203580), a potent, selective antagonist of two specific MAPK kinases-MEK1/MEK2 (U0126)-and a selective antagonist of mitogen-activated protein kinase kinase (MAPKK) (PD-98059), as well as by treatment with wortmannin or LY-294002 (both are selective antagonists of PI-3Ks). Inhibitory concentration 50 (IC(50)) levels obtained for these seven antagonists were consistent with reported inhibition constant (Ki) values for these tyrosine kinase, MAPK, and MAPKK antagonists. Ethanol-induced transient and sustained increases in [Ca(2+)](i) in primary single smooth muscle cells from rat aorta were markedly attenuated in the presence of genistein, an SH2 domain inhibitor peptide, SB-203580, U0126, PD-98059, wortmannin, and LY-294002. A variety of specific antagonists of known endogenously formed vasoconstrictors did not inhibit or attenuate either the ethanol-induced contractions or the elevations of [Ca(2+)](i). Results of the present study support the suggestion that activation of tyrosine kinases (including the src family of cytoplasmic tyrosine kinases), PI-3Ks, and MAPK seems to play an important role in ethanol-induced contractions and the elevation of [Ca(2+)](i) in smooth muscle cells from rat aorta. These signaling pathways thus may be important in hypertension in human beings associated with chronic alcohol consumption.
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Affiliation(s)
- Zhi-wei Yang
- Department of Physiology and Pharmacology, State University of New York, Health Science Center at Brooklyn, Brooklyn, NY 11203, USA
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12
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Li W, Zheng T, Babu AN, Altura BT, Gupta RK, Altura BM. Importance of magnesium ions in development of tolerance to ethanol: studies on cultured cerebral vascular smooth muscle cells, type-2 astrocytes and intact rat brain. Brain Res Bull 2001; 56:153-8. [PMID: 11704353 DOI: 10.1016/s0361-9230(01)00606-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
This study was designed to examine the roles of intracellular free magnesium ion concentration ([Mg(2+)](i)) in ethanol-induced intoxication and development of tolerance in cultured canine cerebral vascular smooth muscle cells and astrocytes as well as intact rat brain. The basal, resting level of [Mg(2+)](i) in cerebrovascular cells was 732.5 +/- 82.4 microM. Exposure of cultured canine cerebral vascular smooth muscle cells to ethanol (10 and 25 mM) for 24 h reduced the concentrations of [Mg(2+)](i) to 521.1 +/- 59.6 microM, and 308.2 +/- 37.8 microM, respectively. However, exposure of these cultured vascular cells to the same concentrations of ethanol, after initial pretreatment with ethanol for 24 h, failed to interfere with the levels of [Mg(2+)](i). Measurement of [Mg(2+)](i) at 48 h and 72 h indicated that the decreased levels of [Mg(2+)](i) induced by ethanol at 24 h treatment returned toward baseline. Similar experiments were performed in cultured type-2 astrocytes isolated from neonatal rat brain. The basal level of [Mg(2+)](i) in type-2 astrocytes was about 125 microM. Incubation of these cells with 10 mM ethanol for 10 min resulted in a 27% reduction in the level of [Mg(2+)](i), whereas incubation with 25 mM ethanol resulted in almost a 50% reduction in [Mg(2+)](i). The decreased levels of [Mg(2+)](i) lasted around 30 min, until the measurement finished. Continuous incubation of these cultured astrocytes, with ethanol (either 10 mM or 25 mM), for more than 24 h, indicated that the concentrations of [Mg(2+)](i) in type-2 astrocytes were equivalent to those at basal, resting levels. In vivo 31P-NMR spectroscopy, performed on intact rat brains, indicated that an initial administration of 4 mg/kg ethanol ( approximately 20-25 mM blood alcohol level) resulted (after 20-40 min of exposure) in severe deficits in whole brain [Mg(2+)](i) (550 +/- 33 microM to 358 +/- 24 microM). Repeated injections of ethanol (4 mg/kg) over the next 24-72 h resulted in progressively diminishing effects on brain [Mg(2+)](i). These experimental data indicate that chronic ethanol treatment can induce a tolerance to depletion of [Mg(2+)](i) in cerebrovascular smooth muscle cells, type-2 astrocytes as well as intact rat brain. The results suggest that [Mg(2+)](i) might play a major role in alcohol-induced tolerance in the brain.
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MESH Headings
- Alcohol-Induced Disorders, Nervous System/metabolism
- Alcohol-Induced Disorders, Nervous System/physiopathology
- Animals
- Animals, Newborn
- Astrocytes/drug effects
- Astrocytes/metabolism
- Blood-Brain Barrier/drug effects
- Blood-Brain Barrier/physiology
- Brain/drug effects
- Brain/metabolism
- Brain/physiopathology
- Cells, Cultured/drug effects
- Cells, Cultured/metabolism
- Cerebral Arteries/drug effects
- Cerebral Arteries/metabolism
- Cerebral Arteries/physiopathology
- Dogs
- Dose-Response Relationship, Drug
- Drug Administration Schedule
- Drug Tolerance/physiology
- Ethanol/pharmacology
- Intracellular Fluid/drug effects
- Intracellular Fluid/metabolism
- Magnesium/metabolism
- Male
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/metabolism
- Rats
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Affiliation(s)
- W Li
- Department of Physiology and Pharmacology, State University of New York, Downstate Medical Center, Brooklyn, NY 11023, USA
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13
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Li W, Zheng T, Altura BT, Altura BM. Antioxidants prevent depletion of [Mg2+]i induced by alcohol in cultured canine cerebral vascular smooth muscle cells: possible relationship to alcohol-induced stroke. Brain Res Bull 2001; 55:475-8. [PMID: 11543947 DOI: 10.1016/s0361-9230(01)00547-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Low serum concentrations of Mg(2+) ions have been reported, recently, in patients with coronary disease, atherosclerosis, and stroke as well as in patients with cerebral hemorrhage. The aim of the present study was to determine whether potent antioxidants [alpha-tocopherol and pyrrolidine dithiocarbamate (PDTC)] can prevent or ameliorate intracellular Mg(2+) ([Mg(2+)](i)) depletion associated with cerebral vascular injury induced by alcohol. Exposure of cultured canine cerebral vascular smooth muscle cells to alcohol (10-100 mM) for 24 h induced marked depletion in [Mg(2+)](i) (i.e., approximately 30-65%, depending upon alcohol concentration). Treatment of the cultured cells with either PDTC (0.1 microM) or alpha-tocopherol (15 microM) for 24 h, alone, failed to interfere with basal [Mg(2+)](i) levels. However, preincubation of the cells with either alpha-tocopherol or PDTC for 24 h completely inhibited the depletion of [Mg(2+)](i) induced by exposure to 10-100 mM ethanol. These results indicate that alpha-tocopherol and PDTC prevent decreases in [Mg(2+)](i) produced by ethanol. Moreover, these new results suggest that such protective effects of alpha-tocopherol and PDTC on cerebral vascular cells might be useful therapeutic tools in prevention and amelioration of cerebral vascular injury and stroke in alcoholics.
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Affiliation(s)
- W Li
- Department of Physiology and Pharmacology, State University of New York, Health Science Centre at Brooklyn, Brooklyn, NY 11203, USA
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14
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Yang ZW, Wang J, Zheng T, Altura BT, Altura BM. Importance of PKC and PI3Ks in ethanol-induced contraction of cerebral arterial smooth muscle. Am J Physiol Heart Circ Physiol 2001; 280:H2144-52. [PMID: 11299216 DOI: 10.1152/ajpheart.2001.280.5.h2144] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We investigated the relationships of two potential intracellular signaling pathways, protein kinase C (PKC) and phosphatidylinositol 3-kinases (PI3Ks), to ethanol-induced contractions in cerebral arteries. Ethanol (20-200 mM) induces concentration-dependent constriction in isolated canine basilar arteries that is inhibited in a concentration-dependent manner by pretreatment of these vessels with 10(-9)-10(-3) M Gö-6976 (an antagonist selective for PKC-alpha and PKC-betaI), 10(-10)-10(-4) M bisindolylmaleimide I (a specific antagonist of PKC), and 10(-10)-10(-4) M wortmannin or 10(-8)-10(-2) M LY-294002 (selective antagonists of PI3Ks). Ethanol-induced increases in intracellular Ca(2+) concentration (from approximately 100 to approximately 500 nM) in canine basilar smooth muscle cells are also suppressed markedly (approximately 20-70%) in the presence of a similar concentration range of Gö-6976, bisindolymaleimide I, wortmannin, or LY-294002. This study suggests that activation of PKC isoforms and PI3Ks appears to be an important signaling pathway in ethanol-induced vasoconstriction of cerebral blood vessels.
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Affiliation(s)
- Z W Yang
- Department of Physiology and Pharmacology, Health Science Center at Brooklyn, State University of New York, Brooklyn, New York 11203, USA
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