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Annual Review of Nutrition 2015This article summarizes current data and approaches to assess sodium intake in individuals and populations. A review of the literature on sodium excretion and intake... (Review)
Review
This article summarizes current data and approaches to assess sodium intake in individuals and populations. A review of the literature on sodium excretion and intake estimation supports the continued use of 24-h urine collections for assessing population and individual sodium intake. Since 2000, 29 studies used urine biomarkers to estimate population sodium intake, primarily among adults. More than half used 24-h urine; the rest used a spot/casual, overnight, or 12-h specimen. Associations between individual sodium intake and health outcomes were investigated in 13 prospective cohort studies published since 2000. Only three included an indicator of long-term individual sodium intake, i.e., multiple 24-h urine specimens collected several days apart. Although not insurmountable, logistic challenges of 24-h urine collection remain a barrier for research on the relationship of sodium intake and chronic disease. Newer approaches, including modeling based on shorter collections, offer promise for estimating population sodium intake in some groups.
Topics: Adolescent; Adult; Biomarkers; Child; Chronic Disease; Climate; Cohort Studies; Environment; Exercise; Female; Health Status; Humans; Ion-Selective Electrodes; Life Style; Male; Natriuresis; Potassium, Dietary; Prospective Studies; Sodium; Sodium, Dietary
PubMed: 25974702
DOI: 10.1146/annurev-nutr-071714-034322 -
American Journal of Veterinary Research Mar 2005To compare effects of oral supplementation with an experimental potassium-free sodium-abundant electrolyte mixture (EM-K) with that of oral supplementation with... (Comparative Study)
Comparative Study
OBJECTIVE
To compare effects of oral supplementation with an experimental potassium-free sodium-abundant electrolyte mixture (EM-K) with that of oral supplementation with commercial potassium-rich mixtures (EM+K) on acid-base status and plasma ion concentrations in horses during an 80-km endurance ride.
ANIMALS
46 healthy horses.
PROCEDURE
Blood samples were collected before the ride; at 21-, 37-, 56-, and 80-km inspection points; and during recovery (ie, 30-minute period after the ride). Consumed electrolytes were recorded. Blood was analyzed for pH, PvCO2, and Hct, and plasma was analyzed for Na+, K+, Cl-, Ca2+, Mg2+, lactate, albumin, phosphate, and total protein concentrations. Plasma concentrations of H+ and HCO3-, the strong ion difference (SID), and osmolarity were calculated.
RESULTS
34 (17 EM-K and 17 EM+K treated) horses finished the ride. Potassium intake was 33 g less and Na+ intake was 36 g greater for EM-K-treated horses, compared with EM+K-treated horses. With increasing distance, plasma osmolarity; H+, Na+, K+, Mg2+, phosphate, lactate, total protein, and albumin concentrations; and PvCO2 and Hct were increased in all horses. Plasma HCO3-, Ca2+, and Cl- concentrations were decreased. Plasma H+ concentration was significantly lower in EM-K-treated horses, compared with EM+K-treated horses. Plasma K+ concentrations at the 80-km inspection point and during recovery were significantly less in EM-K-treated horses, compared with EM+K-treated horses.
CONCLUSIONS AND CLINICAL RELEVANCE
Increases in plasma H+ and K+ concentrations in this endurance ride were moderate and unlikely to contribute to signs of muscle fatigue and hyperexcitability in horses.
Topics: Acid-Base Equilibrium; Analysis of Variance; Animals; Blood Chemical Analysis; Electrolytes; Horses; Hydrogen-Ion Concentration; Ions; Muscle, Skeletal; Osmolar Concentration; Physical Exertion; Potassium, Dietary
PubMed: 15822592
DOI: 10.2460/ajvr.2005.66.466 -
Journal of the American Chemical Society Aug 2023The potassium ion (K) configurations of the selectivity filter of the KcsA ion channel protein are investigated with two-dimensional infrared (2D IR) spectroscopy of...
The potassium ion (K) configurations of the selectivity filter of the KcsA ion channel protein are investigated with two-dimensional infrared (2D IR) spectroscopy of amide I vibrations. Single C-O isotope labels are used, for the first time, to selectively probe the S1/S2 or S2/S3 binding sites in the selectivity filter. These binding sites have the largest differences in ion occupancy in two competing K transport mechanisms: soft-knock and hard-knock. According to the former, water molecules alternate between K ions in the selectivity filter while the latter assumes that K ions occupy the adjacent sites. Molecular dynamics simulations and computational spectroscopy are employed to interpret experimental 2D IR spectra. We find that in the closed conductive state of the KcsA channel, K ions do not occupy adjacent binding sites. The experimental data is consistent with simulated 2D IR spectra of soft-knock ion configurations. In contrast, the simulated spectra for the hard-knock ion configurations do not reproduce the experimental results. 2D IR spectra of the hard-knock mechanism have lower frequencies, homogeneous 2D lineshapes, and multiple peaks. In contrast, ion configurations of the soft-knock model produce 2D IR spectra with a single peak at a higher frequency and inhomogeneous lineshape. We conclude that under equilibrium conditions, in the absence of transmembrane voltage, both water and K ions occupy the selectivity filter of the KcsA channel in the closed conductive state. The ion configuration is central to the mechanism of ion transport through potassium channels.
Topics: Potassium Channels; Potassium; Spectrophotometry, Infrared; Isotopes; Ions; Water; Bacterial Proteins; Protein Conformation
PubMed: 37578394
DOI: 10.1021/jacs.3c05339 -
PloS One 2013Voltage-sensitive potassium ion channels are essential for life, but the molecular basis of their ion conduction is not well understood. In particular, the impact of ion...
Voltage-sensitive potassium ion channels are essential for life, but the molecular basis of their ion conduction is not well understood. In particular, the impact of ion concentration on ion conduction has not been fully studied. We performed several micro-second molecular dynamics simulations of the pore domain of the Kv1.2 potassium channel in KCl solution at four different ion concentrations, and scrutinized each of the conduction events, based on graphical representations of the simulation trajectories. As a result, we observed that the conduction mechanism switched with different ion concentrations: at high ion concentrations, potassium conduction occurred by Hodgkin and Keynes' knock-on mechanism, where the association of an incoming ion with the channel is tightly coupled with the dissociation of an outgoing ion, in a one-step manner. On the other hand, at low ion concentrations, ions mainly permeated by a two-step association/dissociation mechanism, in which the association and dissociation of ions were not coupled, and occurred in two distinct steps. We also found that this switch was triggered by the facilitated association of an ion from the intracellular side within the channel pore and by the delayed dissociation of the outermost ion, as the ion concentration increased.
Topics: Ion Transport; Ions; Kv1.2 Potassium Channel; Models, Biological; Models, Chemical; Models, Molecular; Molecular Dynamics Simulation; Potassium; Potassium Channels; Protein Conformation
PubMed: 23418558
DOI: 10.1371/journal.pone.0056342 -
The Journal of Nutrition Nov 2004Potassium (K+) requirements have been largely overlooked because severe deficiencies are uncommon due to the ubiquity of this element in foods. However, a transition... (Review)
Review
Potassium (K+) requirements have been largely overlooked because severe deficiencies are uncommon due to the ubiquity of this element in foods. However, a transition toward modern ("Westernized") diets has led to a substantial decline of K+ intake compared with traditional food habits, and a large fraction of the population might now have suboptimal K+ intake. A high K+ intake was demonstrated to have protective effects against several pathologic states affecting the cardiovascular system, kidneys, and bones. Additionally, fruits and vegetables contain K/organic anion salts (malate, citrate), which exert alkalinizing effects, through KHCO(3)(-) generation, which serves to neutralize fixed acidity in urine. Low-grade metabolic acidosis, when not properly controlled, may exacerbate various catabolic processes (bone Ca++ mobilization, proteolysis), especially in the elderly. Fruits and vegetables are therefore receiving great attention in a strategy to increase the nutritional value of meals while reducing energy density and intake. The need to ensure a 2.5- to 3.5-g daily K+ supply from fruits and vegetables represents a strong rationale for the "5-10 servings per day" recommendations.
Topics: Acid-Base Equilibrium; Blood Glucose; Bone Diseases; Cardiovascular Diseases; Cations, Divalent; Fruit; Humans; Hydrogen-Ion Concentration; Kidney Diseases; Nutritional Physiological Phenomena; Potassium, Dietary; Urine; Vegetables
PubMed: 15514249
DOI: 10.1093/jn/134.11.2903 -
Nutrients Jul 2022The excess sodium (Na) intake and insufficient potassium (K) intake are frequently observed all over the world, including Indonesia. This study explored the dietary...
The excess sodium (Na) intake and insufficient potassium (K) intake are frequently observed all over the world, including Indonesia. This study explored the dietary patterns of Indonesian people and evaluated their associations with Na and K intakes. Na and K intakes were assessed by repeated 24-h urine collection. The dietary patterns of the previous month were extracted by factor analysis using the Indonesian Food Frequency Questionnaire. The participants were community-dwelling Indonesian men and women (n = 479) aged 20 years and over. We identified four dietary patterns in each sex. After controlling for confounding factors, the high quantile of ‘Noodle, oil, and salty sea products’ pattern was associated with the high Na intake in both men and women (p = 0.02 and <0.001, respectively). The ‘Meat, vegetable, oil, and fruit’ pattern statistically significantly contributed to the high K intake in men (p = 0.04), but not in women (p = 0.26). The ‘Vegetable, non-oil, and milk’ pattern in men and ‘Meat, vegetable, and fruit’ pattern in women were associated with low Na:K ratios (p = 0.03 and 0.01, respectively). Neither ‘bread’ nor ‘fish’ appeared as a major determinant of any dietary patterns in this population. The ‘Noodle, oil, and salty sea products’ pattern should be avoided to reduce sodium intake.
Topics: Adult; Diet; Female; Humans; Indonesia; Ions; Male; Potassium; Potassium, Dietary; Sodium; Sodium, Dietary; Urine Specimen Collection; Vegetables
PubMed: 35889861
DOI: 10.3390/nu14142905 -
The Journal of Nutrition Jan 2008The calcium economy is a dynamic state influenced by fluxes in dietary calcium intake, intestinal calcium absorption, and renal calcium conservation. The relationship of... (Review)
Review
The calcium economy is a dynamic state influenced by fluxes in dietary calcium intake, intestinal calcium absorption, and renal calcium conservation. The relationship of selected bone-related nutrients to these calcium fluxes exhibits both constructive and destructive interactions that affect the overall state of calcium balance. The basis of the calcium requirement and the impact of vitamin D, protein, phosphorus, sodium, and caffeine on the calcium economy are reviewed. Against this background, emerging data on potassium are presented. Data from balance studies of healthy white women at midlife were reviewed to assess the effect of diet potassium on the calcium economy under steady-state conditions. Potassium was inversely associated with both urinary calcium excretion and intestinal calcium absorption, yielding no significant net change in calcium balance. In the population reported on here, dairy, meat, and cereal grains together contributed 56%, and fruits and vegetables 44%, of total dietary potassium. To the extent that fruit and vegetable potassium is a surrogate for high bicarbonate, this cohort did not have a dietary intake pattern allowing for measurement or interpretation of the potential effect of a high-bicarbonate-containing diet on long-term steady-state calcium balance. Potassium itself is uniformly well absorbed regardless of the dietary source. Mean 24-h urinary potassium averaged 92% of dietary intake. According to nationwide food consumption surveys, milk is the number 1 single food source of potassium in all age groups in the United States.
Topics: Bicarbonates; Calcium; Diet; Female; Fruit; Humans; Nutrition Surveys; Nutritional Physiological Phenomena; Osteoporosis; Potassium; Vegetables
PubMed: 18156419
DOI: 10.1093/jn/138.1.166S -
PLoS Pathogens Feb 2019Successful host colonization by bacteria requires sensing and response to the local ionic milieu, and coordination of responses with the maintenance of ionic homeostasis...
Successful host colonization by bacteria requires sensing and response to the local ionic milieu, and coordination of responses with the maintenance of ionic homeostasis in the face of changing conditions. We previously discovered that Mycobacterium tuberculosis (Mtb) responds synergistically to chloride (Cl-) and pH, as cues to the immune status of its host. This raised the intriguing concept of abundant ions as important environmental signals, and we have now uncovered potassium (K+) as an ion that can significantly impact colonization by Mtb. The bacterium has a unique transcriptional response to changes in environmental K+ levels, with both distinct and shared regulatory mechanisms controlling Mtb response to the ionic signals of K+, Cl-, and pH. We demonstrate that intraphagosomal K+ levels increase during macrophage phagosome maturation, and find using a novel fluorescent K+-responsive reporter Mtb strain that K+ is not limiting during macrophage infection. Disruption of Mtb K+ homeostasis by deletion of the Trk K+ uptake system results in dampening of the bacterial response to pH and Cl-, and attenuation in host colonization, both in primary murine bone marrow-derived macrophages and in vivo in a murine model of Mtb infection. Our study reveals how bacterial ionic homeostasis can impact environmental ionic responses, and highlights the important role that abundant ions can play during host colonization by Mtb.
Topics: Adaptation, Biological; Animals; Bacterial Proteins; Homeostasis; Host Microbial Interactions; Host-Pathogen Interactions; Ions; Macrophages; Mice; Mice, Inbred C57BL; Mycobacterium tuberculosis; Phagosomes; Potassium
PubMed: 30716121
DOI: 10.1371/journal.ppat.1007591 -
Journal of the American Chemical Society Mar 2022The flow of ions across cell membranes facilitated by ion channels is an important function for all living cells. Despite the huge amount of structural data provided by...
The flow of ions across cell membranes facilitated by ion channels is an important function for all living cells. Despite the huge amount of structural data provided by crystallography, elucidating the exact interactions between the selectivity filter atoms and bound ions is challenging. Here, we detect bound N-labeled ammonium ions as a mimic for potassium ions in ion channels using solid-state NMR under near-native conditions. The non-selective ion channel NaK showed two ammonium peaks corresponding to its two ion binding sites, while its potassium-selective mutant NaK2K that has a signature potassium-selective selectivity filter with four ion binding sites gave rise to four ammonium peaks. Ions bound in specific ion binding sites were identified based on magnetization transfer between the ions and carbon atoms in the selectivity filters. Magnetization transfer between bound ions and water molecules revealed that only one out of four ions in the selectivity filter of NaK2K is in close contact with water, which is in agreement with the direct knock-on ion conduction mechanism where ions are conducted through the channel by means of direct interactions without water molecules in between. Interestingly, the potassium-selective ion channels investigated here (NaK2K and, additionally, KcsA-Kv1.3) showed remarkably different chemical shifts for their bound ions, despite having identical amino acid sequences and crystal structures of their selectivity filters. Molecular dynamics simulations show similar ion binding and conduction behavior between ammonium and potassium ions and identify the origin of the differences between the investigated potassium channels.
Topics: Ammonium Compounds; Bacterial Proteins; Ions; Molecular Dynamics Simulation; Potassium; Potassium Channels; Protein Conformation; Water
PubMed: 35200002
DOI: 10.1021/jacs.1c13247 -
JCI Insight Jan 2021Kir5.1 is an inwardly rectifying potassium (Kir) channel subunit abundantly expressed in the kidney and brain. We previously established the physiologic consequences of...
Kir5.1 is an inwardly rectifying potassium (Kir) channel subunit abundantly expressed in the kidney and brain. We previously established the physiologic consequences of a Kcnj16 (gene encoding Kir5.1) knockout in the Dahl salt-sensitive rat (SSKcnj16-/-), which caused electrolyte/pH dysregulation and high-salt diet-induced mortality. Since Kir channel gene mutations may alter neuronal excitability and are linked to human seizure disorders, we hypothesized that SSKcnj16-/- rats would exhibit neurological phenotypes, including increased susceptibility to seizures. SSKcnj16-/- rats exhibited increased light sensitivity (fMRI) and reproducible sound-induced tonic-clonic audiogenic seizures confirmed by electroencephalography. Repeated seizure induction altered behavior, exacerbated hypokalemia, and led to approximately 38% mortality in male SSKcnj16-/- rats. Dietary potassium supplementation did not prevent audiogenic seizures but mitigated hypokalemia and prevented mortality induced by repeated seizures. These results reveal a distinct, nonredundant role for Kir5.1 channels in the brain, introduce a rat model of audiogenic seizures, and suggest that yet-to-be identified mutations in Kcnj16 may cause or contribute to seizure disorders.
Topics: Acoustic Stimulation; Animals; Disease Models, Animal; Electroencephalography; Epilepsy, Reflex; Female; Gene Knockout Techniques; Humans; Hypokalemia; Male; Mutation; Potassium Channels, Inwardly Rectifying; Potassium, Dietary; Rats; Rats, Inbred Dahl; Rats, Transgenic; Seizures; Severity of Illness Index; Kir5.1 Channel
PubMed: 33232300
DOI: 10.1172/jci.insight.143251