Potassium In Man Research Articles

Bias in protein and potassium intake collected with 24-h recalls (EPIC-Soft) is rather comparable across European populations

PurposeWe investigated whether group-level bias of a 24-h recall estimate of protein and potassium intake, as compared to biomarkers, varied across European centers and whether this was influenced by characteristics of individuals or centers.MethodsThe combined data from EFCOVAL and EPIC studies included 14 centers from 9 countries (n = 1,841). Dietary data were collected using a computerized 24-h recall (EPIC-Soft). Nitrogen and potassium in 24-h urine collections were used as reference method. Multilevel linear regression analysis was performed, including individual-level (e.g., BMI) and center-level (e.g., food pattern index) variables.ResultsFor protein intake, no between-center variation in bias was observed in men while it was 5.7% in women. For potassium intake, the between-center variation in bias was 8.9% in men and null in women. BMI was an important factor influencing the biases across centers (p < 0.01 in all analyses). In addition, mode of administration (p = 0.06 in women) and day of the week (p = 0.03 in men and p = 0.06 in women) may have influenced the bias in protein intake across centers. After inclusion of these individual variables, between-center variation in bias in protein intake disappeared for women, whereas for potassium, it increased slightly in men (to 9.5%). Center-level variables did not influence the results.ConclusionThe results suggest that group-level bias in protein and potassium (for women) collected with 24-h recalls does not vary across centers and to a certain extent varies for potassium in men. BMI and study design aspects, rather than center-level characteristics, affected the biases across centers.Electronic supplementary materialThe online version of this article (doi:10.1007/s00394-011-0279-z) contains supplementary material, which is available to authorized users.

Nutritional status of adventure racers

Objective We describe the usual food intake, body composition, and biochemical profile of adventure racers during their training season and evaluate their energy and nutrient intake in relation to current recommendations for ultraendurance athletes. Methods Twenty-four adventure race athletes (18 men and 6 women), 24 to 42 y of age, participated in the study. Food intake was determined with a 3-d food record and body composition by plethysmography. Blood samples were obtained from all subjects for biochemical analyses. All assessments were made during the usual training phase. Results Female athletes had a higher body fat percentage than did male athletes (20.2 ± 5.7% versus 12.5 ± 3.5%). For men and women, food intake was high in protein (1.9 ± 0.5 g/kg in men, 2.0 ± 0.4 g/kg in women) and fat (1.6 ± 0.3 g/kg in men, 1.5 ± 1.3 g/kg in women). Carbohydrate intake of male athletes was at the lower limit of that recommended (5.9 ± 1.8 g/kg). For most vitamins and minerals, athletes’ intake was adequate, with the exception of magnesium, zinc, and potassium in men and women and vitamin E and calcium in women, which presented a high probability of being inadequate compared with reference values. High blood levels of total cholesterol and low-density lipoprotein cholesterol were found in female athletes (201.0 ± 44.7 and 104.1 ± 43.1 mg/dL, respectively) and all other biochemical analyses were within normal reference values. Conclusion The adventure racers presented an inadequate nutritional profile when compared with recommendations for endurance exercise. These athletes need to be educated about consuming an adequate diet to meet the nutritional needs of their activity.

Demographic and nutritional profiles of people consuming varying levels of added sugars

Sociodemographic characteristics and dietary intake of high and low consumers of added sugars, was assessed on a random sample of the Australian adult population using a postal, quantified food frequency approach. People with a higher percentage of energy coming from added sugars in their diet had higher energy and fibre intakes, but lower % energy from fat, complex carbohydrates, protein and alcohol. They also had lower intakes of a range of micronutrients despite having a higher energy intake. However, the form of the relationship between % added sugars and micronutrient intake varied. For some there was a strong linear trend across deciles of added sugars intake with vitamin B6, beta-carotene, folate and magnesium showing the strongest inverse linear trends in both men and women. In women, there was also a strong trend for niacin and weaker but still significant inverse linear trends for retinol, vitamin C, vitamin B12, potassium and zinc. In men, weaker trends were evident for vitamin B12, sodium, calcium and zinc. There were no significant linear trends for thiamine, riboflavin or iron in either sex, nor for retinol, vitamin C or potassium in men and sodium and calcium in women. For some of the micronutrients however, the relationship between % added sugars and micronutrient intake was not strictly linear, with lower nutrient intakes occurring at either end of the % added sugars intake range. High consumers of added sugars were found in all sociodemographic sectors but more particularly so in men and amongst smokers. For women, younger respondents and those in the paid workforce were more likely to be high consumers and, for men, consumption was more likely to be high in those who had never married.

Renal Excretion of Potassium in Men under Hypokinesia and Physical Exercise with Chronic Rehydration

Renal Excretion of Potassium in Men under Hypokinesia and Physical Exercise with Chronic Rehydration

Effect of Bicycle Exercise on Plasma Potassium in Man

Effect of Bicycle Exercise on Plasma Potassium in Man

Intracellular concentration and transmembrane fluxes of sodium and potassium in erythrocytes of normal men and women

The intracellular concentration and transmembrane fluxes of sodium and potassium were studied in the red blood cells of normal men and women in the two halves of their menstrual cycle. Compared to men, the intra-erythrocyte sodium concentration was lower in women during the second half of the menstrual cycle. These two groups were similar for Na+, K+-ATPase pump activity estimated from the ouabain-sensitive 86rubidium-uptake and for the furosemide-sensitive sodium and potassium efflux. Women in the first half of the menstrual cycle, had intra-erythrocyte sodium concentration similar to men, but their furosemide-sensitive sodium efflux was lower. A lower intra-erythrocyte sodium concentration was observed in the second half as compared to the first half of the menstrual cycle in women. No significant difference was observed in the intra-erythrocyte potassium concentration and transmembrane fluxes of potassium in men and women in either half of the menstrual cycle. Therefore one should take into account sex-related variability when studying cationic fluxes and concentrations in red blood cells of men and women.

Body sodium and potassium in men with spinal cord injury.

As part of a broad study on the body composition of patients with extensive muscular paralysis, total body water (TBW), extracellular fluid (ECF), exchangeable sodium (Nae), and exchangeable potassium (Ke) were measured in 22 paraplegic and 23 quadriplegic patients. These data were compared with similar measurements obtained on 12 healthy men. Patients with spinal cord injury (SCI) showed a drastic loss of K+, more pronounced in quadriplegic than in paraplegic patients. Sodium was retained and associated with a relatively increased ECF volume. The high correlation between TBW and total "exchangeable base" (Nae + Ke) reported in previous studies on healthy subjects and patients with varied diseases was also observed in SCI patients. Analysis of the present data suggests that the physiologic mechanism which maintains the tonicity of the body fluids is not affected in SCI. This analysis does not provide any clue as to the identification of the mechanism that might explain the relative expansion of the extracellular space in the presence of K+ depletion.

Intracellular potassium in man. A comparison of in vivo and in vitro measurement techniques

In order to evaluate different methods of estimating intracellular content of potassium, determinations of potassium were made in erythrocytes, in muscle biopsy specimens and in the total body. The total body potassium (TBK) was related to body weight (Bwt), lean body mass (LBM), dry LBM, soft fat-free solids (SFFS), total body water (TBW) and calculated intracellular fluid (ICF). Sixty-two healthy subjects and 80 patients with various diseases and therapy known to influence the potassium metabolism were studied. Statistically significant correlations were found between potassium content in muscle biopsies related to fat-free solids and TBK/Bwt (r=+0.56, P<0.05), TBK/LBM (r=+0.58, Plt;0.01), dry LBM (r=+0.54, P<0.05) and TBK/SFFS (r=+0.68, P<0.01). A correlation was found between muscle potassium related to intramuscular water and TBK/TBW (r=+0.47, P<0.05). No correlations were found between EK and TBK/LBM, TBK/dry LBM or TBK/ICF. Between EK and serum potassium a negative correlation (r=−0.31, P<0.05) was found in a group of untreated hypertensives. It is concluded that the quotients of TBK (TBK/LBM, TBK/TBW and TBK/SFFS) might be used in the study of intracellular potassium—at least in the study of patient groups.

Graded dose effects of angiotensin II on aldosterone production in man during various levels of potassium intake

This study was performed to evaluate the hypothesis that adrenal aldosterone output is modulated by daily potassium intake in man. Eight normotensive subjects, aged 24–38 yr, were fed 3 separate 150 mEq sodium-containing diets. Potassium content ranged from 300 mEq daily during the first week, to 80 mEq daily and 10 mEq daily for the subsequent 2 wk. On days 4 and 5 of each diet each subject took oral dexamethasone 0.5 mg B.I.D. to prevent endogenous ACTH secretion. On day 6 an infusion of angiotensin II (AII) was administered in doses of 0.1, 0.3, 1.0, 3.0 and 10.0 ng/kg/min, each lasting 30 min. Blood pressure, pulse, and plasma aldosterone and potassium were measured throughout the infusions. All at infusion rates of 3 and 10 ng/kg/min, produced significant increases in plasma aldosterone values during liberal potassium intake but not when potassium intake was 10 mEq/day. We conclude that dietary potassium in man modulates All-mediated aldosterone secretion.

Effect of digoxin upon intracellular potassium in man.

The effect of digoxin upon intramuscular potassium was studied by use of whole body counting and biopsy technique. Twelve healthy subjects and twelve outpatients with mild cardiac insufficiency or atrial arrhythmia were digitalised. Before and after digitalization total body potassium (TBK) was measured. Potassium concentration in muscle specimens (MK) was analysed by the neutron activation technique. Digoxin was measured in serum and in skeletal muscle tissue by radioimmunoassay, and QS2-index as a measure of the electromechanical systole. In both groups a significant decrease in TBK (P less than 0.05) and MK (P less than 0.01) was demonstrated in connection to digitalization. There was no correlation between the decrease in TBK and MK, or between the concentrations of digoxin in serum or muscle and the decrease in potassium concentration. The digoxin in serum in healthy subjects was 0.9 +/- 0.33 nmol/l and in patients 1.2 +/- 0.41 nmol/l. The digoxin in muscle was 39 +/- 10.9 nmol/kg dry weight in seven of the healthy individuals and 37 +/- 9.5 nmol/kg dry weight in nine patients. After digitalization a decrease of QS2-index was found in both groups (P less than 0.01).

Influence of glucagon on plasma levels of potassium in man.

To investigate the role played by glucagon in the regulation of plasma potassium, we have examined the behaviour of this ion during four 2 h infusions of saline, glucagon (200 ng/min), cyclic somatostatin (priming dose of 50 microgram followed by 5.8 microgram/min) and somatostatin plus glucagon in 6 normal volunteers. Glucagon alone produced no change in potassium, despite an increase in insulin. Somatostatin, in addition to depressing insulin, produced a slight but significant (P < 0.01) increase in potassium (delta max: 0.2-0.8 mmol/1: mean +/- SEM, 0.4 +/- 0.1). Infusion of somatostatin together with glucagon suppressed the glucagon-induced increase in insulin and greatly augmented the increase in blood glucose. Potassium rose significantly more (P < 0.02) than after somatostatin alone (delta max: 0.5-1.3 mmol/l; mean 0.9 +/- 0.1), indicating that hyperkalaemia results from hyperglucagonaemia in the absence of insulin. Evidence is presented that this last phenomenon is not mediated by hyperglycaemia or by a reduction in aldosterone secretion. It is suggested that low blood insulin and increased glucagon could be one of the mechanisms that underlie or magnify the hyperkalaemia observed in cases of serious stress or decompensated diabetes.

Intrarenal distribution of oxalic acid, calcium, sodium, and potassium in man.

The renal papilla in man has been shown to contain a high concentration of oxalate (5 . 5 +/- 0 . 8 mmole/kg wet weight, mean +/- SEM, n = 7 kidneys), and that there is a significant concentration gradient between oxalate in the papilla and that of the medulla (0 . 4 +/- 0 . 08, P < 0 . 05) and the cortex (0 . 3 +/- 0 . 06, P < 0 . 05). Significant calcium and sodium gradients between renal papilla and medulla and cortex were confirmed and parallel that of oxalate. Potassium showed a significant decrease in the papilla (33 . 1 +/- 0 . 9) as compared to the medulla (42 . 1 +/- 1 . 9 P < 0 . 05). The concentrations of oxalate and calcium in the papilla were respectively 25-fold and 6-fold higher than the urinary concentration of oxalate and calcium. It is concluded that these high concentrations of oxalate and calcium in the renal papilla are related to the formation of Randall's plaques and may be an essential factor in the pathogenesis of renal stones which is still far from clear.

Myocardial tissue concentrations of magnesium and potassium in men dying suddenly from ischemic heart disease

Myocardial tissue concentrations of magnesium and potassium in men dying suddenly from ischemic heart disease

Myocardial kinetics of thallium and potassium in man.

Myocardial kinetics of thallium and potassium in man.

Myocardial tissue concentrations of magnesium and potassium in men dying suddenly from ischemic heart disease

Optimum tissue levels of magnesium and potassium ions are essential to the structure and function of the myocardium. We hypothesized that an inapparent deficiency of one or both of these elements might contribute to sudden cardiac death in a susceptible person, and in this study investigated levels of these elements in the myocardium of men experiencing sudden death to determine if there was such an association. Subjects dying suddenly with ischemic heart disease had significantly lower levels of myocardial tissue magnesium and potassium than the controls (men dying of acute trauma). The four lowest potassium values were obtained for the only men in the group with a history of angina (P less than 0.0005). Three of the men with angina also had the lowest tissue magnesium levels (P less than 0.005). The intriguing finding gives support to the hypothesis.

Is thallium-201 of use in the measurement of total exchangeable potassium in man?

Simultaneous measurements of exchangeable potassium were made in seven normal male subjects using potassium-43 and thallium-201. Exchangeable potassium values obtained using the 'thallium-201 space' were unreliable.

Decamethonium and serum potassium in man.

Decamethonium and succinylcholine were used to study the effects of depolarizing muscle relaxants on serum potassium in 60 patinets, free of neuromuscular disease, during major orthopedic surgery. Significant increases in serum K+ were found after administration of decamethonium or succinylcholine in the usual clinical doses. The abnormal elevations of serum K+ found in patients with burns, massive trauma, or muscle denervation are thus accentuations of the process that occurs in normal man following use of these depolarizing drugs. The administration of any depolarizing agent to these abnormal patient groups would, therefore, appear contraindicated.

Simultaneous measurement of total exchangeable potassium and sodium using 43K and 24Na

The simultaneous measurement of total exchangeable potassium and total exchangeable sodium is described using 43K and 24Na in 67 patients. Smaller doses of radioisotope were used than previously reported, but despite this a 44-hr mixing period was achieved for potassium. The coefficients of variation for duplicate estimations of radioactivity (potassium. 2.5%, sodium 1.51%) or for exchangeable electrolyte determinations (K e at 44 hr 1.93%; Na e at 24 hr 1.77%) appear comparable to or better than the results of previous studies. The whole-body radiation dose to the patient was estimated at 17 mrad. Eight patients had independent measurements of body potassium ( 40K), and these were in close agreement with the K e value. It is felt that 43K should replace 42K for the measurement of total exchangeable potassium in man.

Response of plasma aldosterone to angiotensin II, ACTH and potassium in man.

ABSTRACT Plasma aldosterone, corticosterone, cortisol and renin activity have been measured in recumbent normal subjects (n = 3–4) following stimulation with angiotensin II, ACTH and potassium. Control studies on a regular sodium intake show that in the same subject aldosterone and renin activity exhibit no time dependent pattern from 7 a.m. to 11 a.m., while corticosterone and cortisol decrease continuously. Angiotensin II (infusion of 7 ng/kg/min over 1–3 h), ACTH (rapid iv injection of 0.5 mg β1-24 ACTH) and potassium (potassium citrate 30 mEq. po every hour for 3 h) on a regular Na intake induce a reproducible increase of aldosterone. The onset of this increase is observed within 10 min for angiotensin II and ACTH and within 60–90 min for potassium. The range of the rise in aldosterone is about 20–25 ng/100 ml for all 3 stimuli, corresponding to a 3–5 fold increase from basal values. Angiotensin II and potassium are, in the dose used, specific stimuli of aldosterone; ACTH however stimulates aldosterone, corticosterone and cortisol, but to a variable degree and with a different time-course response. On a low sodium intake, a similar aldosterone response pattern is found after stimulation with ACTH, but only exceptionally after stimulation with potassium; after both stimuli values of 55–75 ng/100 ml have been reached.

Physiological variation of total-body potassium in man.

Physiological variation of total-body potassium in man.