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Dumelie JG, Chen Q, Miller D, Attarwala N, Gross SS, Jaffrey SR. Biomolecular condensates create phospholipid-enriched microenvironments. Nat Chem Biol 2024; 20:302-313. [PMID: 37973889 PMCID: PMC10922641 DOI: 10.1038/s41589-023-01474-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2022] [Accepted: 10/08/2023] [Indexed: 11/19/2023]
Abstract
Proteins and RNA can phase separate from the aqueous cellular environment to form subcellular compartments called condensates. This process results in a protein-RNA mixture that is chemically different from the surrounding aqueous phase. Here, we use mass spectrometry to characterize the metabolomes of condensates. To test this, we prepared mixtures of phase-separated proteins and extracts of cellular metabolites and identified metabolites enriched in the condensate phase. Among the most condensate-enriched metabolites were phospholipids, due primarily to the hydrophobicity of their fatty acyl moieties. We found that phospholipids can alter the number and size of phase-separated condensates and in some cases alter their morphology. Finally, we found that phospholipids partition into a diverse set of endogenous condensates as well as artificial condensates expressed in cells. Overall, these data show that many condensates are protein-RNA-lipid mixtures with chemical microenvironments that are ideally suited to facilitate phospholipid biology and signaling.
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Affiliation(s)
- Jason G Dumelie
- Department of Pharmacology, Weill Cornell Medical College, Cornell University, New York, NY, USA
| | - Qiuying Chen
- Department of Pharmacology, Weill Cornell Medical College, Cornell University, New York, NY, USA
| | - Dawson Miller
- Department of Pharmacology, Weill Cornell Medical College, Cornell University, New York, NY, USA
| | - Nabeel Attarwala
- Department of Pharmacology, Weill Cornell Medical College, Cornell University, New York, NY, USA
| | - Steven S Gross
- Department of Pharmacology, Weill Cornell Medical College, Cornell University, New York, NY, USA
| | - Samie R Jaffrey
- Department of Pharmacology, Weill Cornell Medical College, Cornell University, New York, NY, USA.
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Dominguez LJ, Veronese N, Barbagallo M. Magnesium and the Hallmarks of Aging. Nutrients 2024; 16:496. [PMID: 38398820 PMCID: PMC10892939 DOI: 10.3390/nu16040496] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2023] [Revised: 02/01/2024] [Accepted: 02/05/2024] [Indexed: 02/25/2024] Open
Abstract
Magnesium is an essential ion in the human body that regulates numerous physiological and pathological processes. Magnesium deficiency is very common in old age. Age-related chronic diseases and the aging process itself are frequently associated with low-grade chronic inflammation, called 'inflammaging'. Because chronic magnesium insufficiency has been linked to excessive generation of inflammatory markers and free radicals, inducing a chronic inflammatory state, we formerly hypothesized that magnesium inadequacy may be considered among the intermediaries helping us explain the link between inflammaging and aging-associated diseases. We show in this review evidence of the relationship of magnesium with all the hallmarks of aging (genomic instability, telomere attrition, epigenetic alterations, loss of proteostasis, deregulated nutrient sensing, mitochondrial dysfunction, cellular senescence, stem cell exhaustion, altered intercellular communication, disabled autophagy, dysbiosis, and chronic inflammation), which may positively affect the human healthspan. It is feasible to hypothesize that maintaining an optimal balance of magnesium during one's life course may turn out to be a safe and economical strategy contributing to the promotion of healthy aging. Future well-designed studies are necessary to further explore this hypothesis.
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Affiliation(s)
- Ligia J. Dominguez
- School of Medicine, “Kore” University of Enna, 94100 Enna, Italy;
- Geriatric Unit, Department of Medicine, University of Palermo, 90127 Palermo, Italy;
| | - Nicola Veronese
- Geriatric Unit, Department of Medicine, University of Palermo, 90127 Palermo, Italy;
| | - Mario Barbagallo
- Geriatric Unit, Department of Medicine, University of Palermo, 90127 Palermo, Italy;
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Fornal M, Lekki J, Królczyk J, Wizner B, Grodzicki T. Association of sulfur content in erythrocytes with cardiovascular parameters and blood pressure. Clin Hemorheol Microcirc 2021; 79:279-292. [PMID: 34057138 DOI: 10.3233/ch-211117] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
OBJECTIVE The study aims at assessing the relationship between blood pressure, heart geometry parameters, and the erythrocyte content of sulfur, potassium, chlorine and phosphorus, in a group of patients with laboratory systolic and diastolic blood pressure (SBP, DBP) below 140 or 90 mm Hg, respectively, who were otherwise healthy and untreated. METHODS The study group consisted of 42 adults recruited in a primary care setting. The individuals were healthy, not undergoing any therapy and free from smoking. For each individual, data were obtained on: average 24-hour SBP and DBP, left ventricle geometry, complete blood count, lipids profile, fibrinogen, hs-CRP and the erythrocyte concentration of sulfur (S), potassium (K), chlorine (Cl) and phosphorus (P). RESULTS Multivariate regression analysis showed statistically significant relationships of diastolic posterior wall thickness (PWTd) and relative wall thickness (RWT) with the concentration ratio of sulfur and potassium (S/K) in erythrocytes: PWTd and RWT increase as the S/K ratio increases. Also, SBP was found to be positively correlated with the S/K ratio. CONCLUSIONS The increase in sulfur content in RBCs could be an indicator of the downregulation of nitric oxide (NO) erythrocyte bioavailability exerted by endogenously produced hydrogen sulfide (H2S), and, in consequence, a marker of the development of hypertension and/or adverse changes in heart geometry.
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Affiliation(s)
- Maria Fornal
- Department of Internal Medicine and Gerontology, Jagiellonian University Medical College, Krakow, Poland
| | - Janusz Lekki
- Institute of Nuclear Physics PAN, Krakow, Poland
| | - Jarosław Królczyk
- Department of Internal Medicine and Gerontology, Jagiellonian University Medical College, Krakow, Poland
| | - Barbara Wizner
- Department of Internal Medicine and Gerontology, Jagiellonian University Medical College, Krakow, Poland
| | - Tomasz Grodzicki
- Department of Internal Medicine and Gerontology, Jagiellonian University Medical College, Krakow, Poland
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Magnesium in Aging, Health and Diseases. Nutrients 2021; 13:nu13020463. [PMID: 33573164 PMCID: PMC7912123 DOI: 10.3390/nu13020463] [Citation(s) in RCA: 96] [Impact Index Per Article: 32.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2020] [Revised: 01/26/2021] [Accepted: 01/28/2021] [Indexed: 12/15/2022] Open
Abstract
Several changes of magnesium (Mg) metabolism have been reported with aging, including diminished Mg intake, impaired intestinal Mg absorption and renal Mg wasting. Mild Mg deficits are generally asymptomatic and clinical signs are usually non-specific or absent. Asthenia, sleep disorders, hyperemotionality, and cognitive disorders are common in the elderly with mild Mg deficit, and may be often confused with age-related symptoms. Chronic Mg deficits increase the production of free radicals which have been implicated in the development of several chronic age-related disorders. Numerous human diseases have been associated with Mg deficits, including cardiovascular diseases, hypertension and stroke, cardio-metabolic syndrome and type 2 diabetes mellitus, airways constrictive syndromes and asthma, depression, stress-related conditions and psychiatric disorders, Alzheimer's disease (AD) and other dementia syndromes, muscular diseases (muscle pain, chronic fatigue, and fibromyalgia), bone fragility, and cancer. Dietary Mg and/or Mg consumed in drinking water (generally more bioavailable than Mg contained in food) or in alternative Mg supplements should be taken into consideration in the correction of Mg deficits. Maintaining an optimal Mg balance all through life may help in the prevention of oxidative stress and chronic conditions associated with aging. This needs to be demonstrated by future studies.
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Yao C, He Z, Nakano T, Shuai J. Spiking patterns of a neuron model to stimulus: Rich dynamics and oxygen's role. CHAOS (WOODBURY, N.Y.) 2018; 28:083112. [PMID: 30180647 DOI: 10.1063/1.5018707] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2017] [Accepted: 07/23/2018] [Indexed: 06/08/2023]
Abstract
Neuronal spiking patterns, which are of fundamental importance for the understanding of information processing in neural systems, can be generated in response to different stimuli. We here investigate in detail the stimulus-induced spiking patterns in a biologically plausible neuron model in which the oxygen concentration and the dynamical concentrations of potassium, sodium, and chloride are considered. Various types of spiking patterns can be induced by the different external potassium accumulations in response to the stimulus, including two different types of epileptic seizure (SZ) and spreading depression (SD) states, two different mixed states of SD and SZ, SZ state with multi-burst, and tonic firing behaviors. Interestingly, we show that these rich spiking patterns can also be induced by the current stimulus with a low oxygen concentration. Furthermore, we reveal that the stimulus can induce two different phase transitions from the SD state to the SZ state according to the phase transition theory, which results in the different electrical activities. All these findings may provide insight into information processing in neural systems.
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Affiliation(s)
- Chenggui Yao
- Department of Mathematics, Shaoxing University, Shaoxing 312000, China
| | - Zhiwei He
- Department of Mathematics, Shaoxing University, Shaoxing 312000, China
| | - Tadashi Nakano
- Graduate School of Frontier Biosciences, Osaka University, 1-1 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Jianwei Shuai
- Department of Physics, Xiamen University, Xiamen 361005, People's Republic of China
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Wu XX, Shuai J. Effects of extracellular potassium diffusion on electrically coupled neuron networks. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2015; 91:022712. [PMID: 25768536 DOI: 10.1103/physreve.91.022712] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2014] [Indexed: 06/04/2023]
Abstract
Potassium accumulation and diffusion during neuronal epileptiform activity have been observed experimentally, and potassium lateral diffusion has been suggested to play an important role in nonsynaptic neuron networks. We adopt a hippocampal CA1 pyramidal neuron network in a zero-calcium condition to better understand the influence of extracellular potassium dynamics on the stimulus-induced activity. The potassium concentration in the interstitial space for each neuron is regulated by potassium currents, Na(+)-K(+) pumps, glial buffering, and ion diffusion. In addition to potassium diffusion, nearby neurons are also coupled through gap junctions. Our results reveal that the latency of the first spike responding to stimulus monotonically decreases with increasing gap-junction conductance but is insensitive to potassium diffusive coupling. The duration of network oscillations shows a bell-like shape with increasing potassium diffusive coupling at weak gap-junction coupling. For modest electrical coupling, there is an optimal K(+) diffusion strength, at which the flow of potassium ions among the network neurons appropriately modulates interstitial potassium concentrations in a degree that provides the most favorable environment for the generation and continuance of the action potential waves in the network.
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Affiliation(s)
- Xing-Xing Wu
- Department of Physics, Xiamen University, Xiamen 361005, P. R. China
| | - Jianwei Shuai
- Department of Physics, State Key Lab of Cellular Stress Biology, Innovation Center for Cell Signaling Network, and Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry, Xiamen University; Xiamen 361005, P. R. China
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Enhanced multiple vibrational resonances by Na+ and K+ dynamics in a neuron model. Sci Rep 2015; 5:7684. [PMID: 25567752 PMCID: PMC4286765 DOI: 10.1038/srep07684] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2014] [Accepted: 12/08/2014] [Indexed: 12/13/2022] Open
Abstract
Some neuronal receptors perceive external input in the form of hybrid periodic signals. The signal detection may be based on the mechanism of vibrational resonance, in which a system's response to the low frequency signal can become optimal by an appropriate choice of the vibration amplitude of HFS. The vibrational resonance effect is investigated in a neuron model in which the intra- and extra-cellular potassium and sodium concentrations are allowed to evolve temporally, depending on ion currents, Na+-K+ pumps, glial buffering, and ion diffusion. Our results reveal that, compared to the vibrational resonances in the model with constant ion concentrations, the significantly enhanced vibrational multi-resonances can be observed for the single neuron system where the potassium and sodium ion concentrations vary temporally. Thus, in contradiction to a popular view that ion concentrations dynamics play little role in signal detection, we indicate that the neuron's response to an external subthreshold signal can be largely improved by sodium and potassium dynamics.
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Obeid OA, Hachem DH, Ayoub JJ. Refeeding and metabolic syndromes: two sides of the same coin. Nutr Diabetes 2014; 4:e120. [PMID: 24979149 PMCID: PMC4079929 DOI: 10.1038/nutd.2014.21] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/26/2014] [Revised: 05/09/2014] [Accepted: 05/28/2014] [Indexed: 12/13/2022] Open
Abstract
Refeeding syndrome describes the metabolic and clinical changes attributed to aggressive rehabilitation of malnourished subjects. The metabolic changes of refeeding are related to hypophosphatemia, hypokalemia, hypomagnesemia, sodium retention and hyperglycemia, and these are believed to be mainly the result of increased insulin secretion following high carbohydrate intake. In the past few decades, increased consumption of processed food (refined cereals, oils, sugar and sweeteners, and so on) lowered the intake of several macrominerals (mainly phosphorus, potassium and magnesium). This seems to have compromised the postprandial status of these macrominerals, in a manner that mimics low grade refeeding syndrome status. At the pathophysiological level, this condition favored the development of the different components of the metabolic syndrome. Thus, it is reasonable to postulate that metabolic syndrome is the result of long term exposure to a mild refeeding syndrome.
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Affiliation(s)
- O A Obeid
- Department of Nutrition and Food Sciences, Faculty of Agricultural and Food Sciences. American University of Beirut, Beirut, Lebanon
| | - D H Hachem
- Department of Nutrition and Food Sciences, Faculty of Agricultural and Food Sciences. American University of Beirut, Beirut, Lebanon
| | - J J Ayoub
- Department of Nutrition and Food Sciences, Faculty of Agricultural and Food Sciences. American University of Beirut, Beirut, Lebanon
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Wu XX, Shuai JW. Multistability in a neuron model with extracellular potassium dynamics. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2012; 85:061911. [PMID: 23005131 DOI: 10.1103/physreve.85.061911] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/27/2012] [Revised: 04/24/2012] [Indexed: 06/01/2023]
Abstract
Experiments show a primary role of extracellular potassium concentrations in neuronal hyperexcitability and in the generation of epileptiform bursting and depolarization blocks without synaptic mechanisms. We adopt a physiologically relevant hippocampal CA1 neuron model in a zero-calcium condition to better understand the function of extracellular potassium in neuronal seizurelike activities. The model neuron is surrounded by interstitial space in which potassium ions are able to accumulate. Potassium currents, Na{+}-K{+} pumps, glial buffering, and ion diffusion are regulatory mechanisms of extracellular potassium. We also consider a reduced model with a fixed potassium concentration. The bifurcation structure and spiking frequency of the two models are studied. We show that, besides hyperexcitability and bursting pattern modulation, the potassium dynamics can induce not only bistability but also tristability of different firing patterns. Our results reveal the emergence of the complex behavior of multistability due to the dynamical [K{+}]{o} modulation on neuronal activities.
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Affiliation(s)
- Xing-Xing Wu
- Department of Physics and Institute of Theoretical Physics and Astrophysics, Xiamen University, Xiamen 361005, People's Republic of China
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Qian B, Luo Y, Deng Y, Cao L, Yang H, Shen Y, Ping J. Chemical composition, angiotensin-converting enzyme-inhibitory activity and antioxidant activities of few-flower wild rice (Zizania latifolia Turcz.). JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE 2012; 92:159-164. [PMID: 21815157 DOI: 10.1002/jsfa.4557] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/31/2010] [Revised: 04/20/2011] [Accepted: 06/09/2011] [Indexed: 05/31/2023]
Abstract
BACKGROUND The chemical compositions of the stem and leaf sheath of few-flower wild rice were analysed. In addition, their extracts were evaluated for diphenylpicrylhydrazyl (DPPH) free radical-scavenging activity, ferric-reducing antioxidant power and angiotensin-converting enzyme (ACE)-inhibitory activity, since these are important properties of sources of nutraceuticals or functional foods. RESULTS The stems contained more ascorbic acid (0.06 g kg(-1) fresh weight), protein (28.18 g kg(-1) dry weight (DW)), reducing sugars (308.54 g kg(-1) DW), water-soluble pectin (20.63 g kg(-1) DW), Na(2) CO(3) -soluble pectin (44.14 g kg(-1) DW), K (8 g kg(-1) dry matter (DM), S (6 g kg(-1) DM) and P (5 g kg(-1) DM) but less starch, total dietary fibre, Si, Na and Ca than the leaf sheaths. The DPPH free radical-scavenging IC(50) values of the stem and leaf sheath extracts were 19.28 and 21.22 mg mL(-1) respectively. In addition, the ACE-inhibitory IC(50) value of the stem extracts was 38.54 mg mL(-1). CONCLUSION Both the stem and leaf sheath extracts exhibited good antioxidant properties, while good ACE-inhibitory activity was detected only in the phosphate buffer solution extracts of the stem. Few-flower wild rice could be processed into formula feeds for fish, poultry, etc. or functional foods for persons with high blood pressure.
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Affiliation(s)
- Bingjun Qian
- Department of Food Science and Technology, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, China
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Weglicki W, Quamme G, Tucker K, Haigney M, Resnick L. Potassium, Magnesium, and Electrolyte Imbalance and Complications in Disease Management. Clin Exp Hypertens 2009; 27:95-112. [PMID: 15773233 DOI: 10.1081/ceh-200044275] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Electrolyte balance is a critical issue in managing comorbid conditions in both diseased and elderly patients. Patients with hypertension and diabetes need careful regulation of their calcium and magnesium levels, whereas in patients with congestive heart failure, sodium and potassium levels also are critical. Herein we report the outcome of a round table discussion at which issues of renal magnesium clearance, magnesium and arrhythmic risk, ion balance in heart failure, diabetes, ischemic stress, oxidative stress in the cardiomyopathy of magnesium deficiency, roles of magnesium and potassium in bone metabolism and the aging population, and the role of electrolyte balance in hypertension have been discussed. In all these issues the maintaining homeostasis of potassium and magnesium is critical and the various therapies that impact on retaining these ions were discussed. Hallmark studies, i.e., Antihypertensive and Lipid-Lowering Treatment to Prevent Heart Attack Trial and Studies of Left Ventricular Dysfunction, have provided insight into treatment of patients with cardiovascular and progressive heart failure. These studies and the availability of potassium- and magnesium-sparing diuretics for use in these disorders provide relevant perspectives for treatment.
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Affiliation(s)
- William Weglicki
- George Washington University Medical Center, Washington, District of Columbia 20052, USA.
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Russell P, Williams A, Marquez K, Hua T, Ehya F, Hardamon C, Tallman T, Valdez P. Effect of ammonium, sodium, and potassium ions on rabbit muscle phosphofructokinase-1 and adenylate kinase activities. J Enzyme Inhib Med Chem 2009; 24:930-6. [PMID: 19555176 DOI: 10.1080/14756360802448089] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
Abstract
This report shows that 30 nM PFK-1 and 30 nM AK were both affected by the presence of NH(4)(+), Na(+), and K(+) salts but with opposite consequences. Low concentrations of PFK-1 lose about half of its activity as a result of dilution and become susceptible to further activity losses owing to the presence of monovalent salts. On the other hand low concentrations of AK lose about 75 percent of its activity but regains activity losses owing to the presence of monovalent salts. It was determined that regain of AK activity did not appear to be a reflection of a major effect on the K(m) value of either AMP or ATP. Dilution to 30 nM AK resulted in no increase K(m) values compared to K(m) values at 140 nM AK. Dilution caused major decreases in the maximum velocities, V(max), when ATP or fructose 6-phosphate was the variable substrate. It was shown in earlier reports that these same low concentrations of PFK-1 and AK were susceptible inhibitions by ascorbate. These attributes are discussed as they may relate to the role of ascorbate facilitation glycogen synthesis in resting muscle and the role that the cytoskeleton infrastructure scaffold may play is also discussed.
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Affiliation(s)
- Percy Russell
- Department of Biology, University of California 0690, San Diego, La Jolla, CA 92093-0690, USA.
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Sarafidis PA, Bakris GL. Reply. J Am Coll Cardiol 2009. [DOI: 10.1016/j.jacc.2008.12.031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Tsuda K. Electron paramagnetic resonance investigation on modulatory effect of benidipine on membrane fluidity of erythrocytes in essential hypertension. Heart Vessels 2008; 23:134-9. [PMID: 18389339 DOI: 10.1007/s00380-007-1017-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/21/2007] [Accepted: 09/12/2007] [Indexed: 11/30/2022]
Abstract
It has been shown that benidipine, a long-lasting calcium (Ca) channel blocker, may exert its protective effect against vascular disorders by increasing nitric oxide (NO) production. The purpose of the present study was to investigate whether orally administered benidipine might influence the membrane function in patients with essential hypertension. We measured the membrane fluidity of erythrocytes by using an electron paramagnetic resonance (EPR) and spin-labeling method. In the preliminary study using erythrocytes obtained from healthy volunteers, benidipine decreased the order parameter (S) for 5-nitroxide stearate (5-NS) and the peak height ratio (ho/h-1) for 16-NS in the EPR spectra in vitro. The finding indicated that benidipine increased the membrane fluidity and improved the microviscosity of erythrocytes. In addition, it was demonstrated that the effect of benidipine on membrane fluidity of erythrocytes was significantly potentiated by the NO-substrate, L-arginine. In the separate series of the study, we observed that orally administered benidipine for 4 weeks significantly increased the membrane fluidity of erythrocytes with a concomitant increase in plasma NO metabolite levels in hypertensive subjects. The results of the present study demonstrated that benidipine might increase the membrane fluidity and improve the microviscosity of erythrocytes both in vitro and in vivo, to some extent, by the NO-dependent mechanism. Furthermore, it is strongly suggested that orally administered benidipine might have a beneficial effect on the rheologic behavior of erythrocytes and the improvement of the microcirculation in hypertensive subjects.
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Affiliation(s)
- Kazushi Tsuda
- Division of Cardiology, Department of Medicine, Wakayama Medical University, Wakayama, Japan.
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15
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The effect of a dietary supplement of potassium chloride or potassium citrate on blood pressure in predominantly normotensive volunteers. Br J Nutr 2007; 99:1284-92. [PMID: 18053306 DOI: 10.1017/s0007114507864853] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Blood pressure (BP) shows a continuous relationship with the risk of CVD. There is substantial evidence that dietary potassium exerts an anti-pressor effect. Most clinical trials have used KCl. However, the chloride ion may have a pressor effect and in foods potassium is associated with organic anions. In a double-blind randomized placebo-controlled trial we explored the effect on BP of two salts of potassium, KCl and potassium citrate (K-cit), in predominantly young healthy normotensive volunteers. The primary outcome was the change in mean arterial pressure as measured in a clinic setting. After 6 weeks of supplementation, compared with the placebo group (n 31), 30 mmol K-cit/d (n 28) changed mean arterial pressure by -5.22 mmHg (95% CI -8.85, -4.53) which did not differ significantly from that induced by KCl (n 26), -4.70 mmHg (-6.56, -2.84). The changes in systolic and diastolic BP were -6.69 (95% CI -8.85, -4.43) and -4.26 (95% CI -6.31, -2.21) mmHg with K-cit and -5.24 (95% CI -7.43, -3.06) and -4.30 (95% CI -6.39, -2.20) mmHg with KCl, and did not differ significantly between the two treatments. Changes in BP were not related to baseline urinary electrolytes. A greater treatment-related effect was observed in those with higher systolic BP. Increasing dietary potassium could therefore have a significant impact on the progressive rise in BP in the entire population.
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Abstract
OBJECTIVE Abnormalities in physicochemical properties of the cell membranes may underlie the defects that are strongly linked to hypertension. Recent evidence indicates that adiponectin may have protective effects against cardiovascular diseases. The purpose of the present study was to assess the possible link between plasma adiponectin and membrane fluidity in normotensive (NT) and hypertensive (HT) men. RESEARCH METHODS AND PROCEDURES We measured the membrane fluidity (a reciprocal value of membrane microviscosity) of erythrocytes in NT and HT men by using an electron paramagnetic resonance and spin-labeling method. RESULTS The order parameter (S) for the spin label agent (5-nitroxide stearate) and the peak height ratio (h0/h(-1)) for 16-nitroxide stearate in the electron paramagnetic resonance spectra of erythrocytes were significantly higher in HT men than in NT men, indicating that membrane fluidity of erythrocytes was decreased in HT men compared with NT men. Both of plasma adiponectin and nitric oxide (NO) metabolite levels were significantly lower in HT men than in NT men. The plasma adiponectin levels were correlated with plasma NO metabolites. The S and the h0/h(-1) of erythrocytes were inversely correlated with the plasma adiponectin and NO metabolite levels, indicating that the decreased membrane fluidity of erythrocytes was associated with hypoadiponectinemia and reduced plasma NO metabolites. DISCUSSION The results of the present study demonstrated that plasma adiponectin levels were lower in HT men than in NT men and that hypoadiponectinemia was associated with decreased membrane fluidity of erythrocytes. The finding suggests that adiponectin may be linked to the rheologic behavior of the erythrocytes and the microcirculation in men, at least in part, by the NO-dependent mechanism.
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Affiliation(s)
- Kazushi Tsuda
- Division of Cardiology, Department of Medicine, Wakayama Medical University, Kimiidera 811-1, Wakayama 641-8509, Japan.
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Maher AD, Chapman BE, Kuchel PW. 39K nuclear magnetic resonance and a mathematical model of K+ transport in human erythrocytes. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2005; 35:293-301. [PMID: 16341859 DOI: 10.1007/s00249-005-0034-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2005] [Revised: 10/31/2005] [Accepted: 11/13/2005] [Indexed: 10/25/2022]
Abstract
(39)K nuclear magnetic resonance was used to measure the efflux of K(+) from suspensions of human erythrocytes [red blood cells (RBCs)], that occurred in response to the calcium ionophore, A23187 and calcium ions; the latter activate the Gárdos channel. Signals from the intra- and extracellular populations of (39)K(+) were selected on the basis of their longitudinal relaxation times, T (1), by using an inversion- recovery pulse sequence with the mixing time, tau(1), chosen to null one or other of the signals. Changes in RBC volume consequent upon efflux of the ions also changed the T (1) values so a new theory was implemented to obviate a potential artefact in the data analysis. The velocity of the K(+) efflux mediated by the Gárdos channel was 1.19+/-0.40 mmol (L RBC)(-1) min(-1) at 37 degrees C.
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Affiliation(s)
- Anthony D Maher
- School of Molecular and Microbial Biosciences, University of Sydney, 2006 Sydney, NSW, Australia
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Abstract
Our hunter-gatherer ancestors appeared to survive on little salt. When today's rural dwellers move to urban environments, they increase their salt intake and the salt-sensitive among them become prone to age-related increase in blood pressure and hypertension. This paper reviews our knowledge of the mechanisms of salt disposal and plasma volume regulation, salt consumption in human evolution, salt intake and prevalence of hypertension, and the results of interventions aimed at modulating both. Finally, it discusses current hypotheses on the mechanisms of selective pressure that may have favored the emergence of a salt-sensitive, hypertensive genotype. Similar to 'thrifty' genes, which supported energy savers in times of scarcity, but may now be causing obesity and type 2 diabetes, 'thirsty' genes, by acting on salt and water retention, might have helped individuals survive the challenge of volume-depleting illnesses, especially when combined with stress-inducing situations, but may now cause high BP and related damage in the post-reproductive age.
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Abstract
Potassium is the most important ion in the living cell, affecting almost every cellular function. Numerous clinical and epidemiologic studies support the knowledge that potassium is a fundamental factor in blood pressure regulation. The role of potassium in blood pressure regulation is reviewed in this article, focusing on its impact on the vascular vessel and the kidney, which are tissues strongly affected by potassium balance. The role of potassium on nitric oxide synthesis and superoxide formation is analyzed. Finally, the study of cell potassium as a marker for hypertension is discussed.
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Affiliation(s)
- Maria Carolina Delgado
- Division of Cardiovascular Medicine, University of Michigan, 3918 Taubman Center, Ann Arbor, MI 48109, USA.
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Schoeffler AJ, Ruiz CR, Joubert AM, Yang X, LiCata VJ. Salt modulates the stability and lipid binding affinity of the adipocyte lipid-binding proteins. J Biol Chem 2003; 278:33268-75. [PMID: 12794068 DOI: 10.1074/jbc.m304955200] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Adipocyte lipid-binding protein (ALBP or aP2) is an intracellular fatty acid-binding protein that is found in adipocytes and macrophages and binds a large variety of intracellular lipids with high affinity. Although intracellular lipids are frequently charged, biochemical studies of lipid-binding proteins and their interactions often focus most heavily on the hydrophobic aspects of these proteins and their interactions. In this study, we have characterized the effects of KCl on the stability and lipid binding properties of ALBP. We find that added salt dramatically stabilizes ALBP, increasing its Delta G of unfolding by 3-5 kcal/mol. At 37 degrees C salt can more than double the stability of the protein. At the same time, salt inhibits the binding of the fluorescent lipid 1-anilinonaphthalene-8-sulfonate (ANS) to the protein and induces direct displacement of the lipid from the protein. Thermodynamic linkage analysis of the salt inhibition of ANS binding shows a nearly 1:1 reciprocal linkage: i.e. one ion is released from ALBP when ANS binds, and vice versa. Kinetic experiments show that salt reduces the rate of association between ANS and ALBP while simultaneously increasing the dissociation rate of ANS from the protein. We depict and discuss the thermodynamic linkages among stability, lipid binding, and salt effects for ALBP, including the use of these linkages to calculate the affinity of ANS for the denatured state of ALBP and its dependence on salt concentration. We also discuss the potential molecular origins and potential intracellular consequences of the demonstrated salt linkages to stability and lipid binding in ALBP.
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Affiliation(s)
- Allyn J Schoeffler
- Department of Biological Sciences, Louisiana State University, Baton Rouge, Louisiana 70803, USA
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Delgado MC, Delgado-Almeida A. Red blood cell K+ could be a marker of K+ changes in other cells involved in blood pressure regulation. J Hum Hypertens 2003; 17:313-8. [PMID: 12756403 DOI: 10.1038/sj.jhh.1001527] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The aim of this study is to determine whether red blood cell K(+) content (RBC(Ki)) is associated with blood pressure levels and, if so, could RBC(Ki) be a marker of potassium changes in other cells involved in blood pressure regulation. The study was performed on 50 untreated hypertensives, 32 of their offspring and 50 age- and sex-matched controls. Systolic (SBP) and diastolic (DBP) blood pressures, height, weight, plasma, urine and red blood cell electrolytes were measured in all subjects. RBC(Ki) was significantly lower in hypertensives than in offspring of hypertensives and normotensive controls. Offspring of hypertensives had significantly lower RBC(Ki) than normotensive controls. Plasma K(+) was significantly lower both in hypertensives and offspring of hypertensives when compared to normotensive controls. A significant negative correlation was found in hypertensives between RBC(Ki) and DBP (r=-0.27, P=0.04) and in offspring of hypertensives between RBC(Ki) and DBP (r=-0.43, P=0.02). A significant correlation was found in hypertensives between RBC(Ki) and plasma K(+) (r=0.3, P=0.02). A positive correlation with borderline significance was found in hypertensives between RBC(Ki) and ionized Ca(2+) (r=0.2, P=0.1). In conclusion, our results support the hypothesis that RBC(Ki) is associated with blood pressure levels and that the measurement of RBC(Ki) levels may represent a biochemical marker for K(+) changes in other cells involved in blood pressure regulation. Further studies are necessary to explain the exact mechanisms of reduced RBC(Ki) levels in hypertensive patients and their offspring.
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Affiliation(s)
- M C Delgado
- Division of Hypertension, University of Michigan, Ann Arbor, MI 481091, USA.
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