Body Potassium Content Research Articles

Hypermetabolism in clinically stable patients with liver cirrhosis

Hypermetabolism has a negative effect on prognosis in patients with liver cirrhosis. Its exact prevalence and associations with clinical data, the nutritional state, and beta-adrenergic activity are unclear. We investigated resting energy expenditure (REE) in 473 patients with biopsy-proven liver cirrhosis. This was a cross-sectional study with a controlled intervention (beta-blockade) in a subgroup of patients. Mean REE was 7.12 +/- 1.34 MJ/d and correlated closely with predicted values (r = 0.70, P < 0.0001). Hypermetabolism was seen in 160 patients with cirrhosis (33.8% of the study population). REE was > 30% above the predicted value in 41% of the hypermetabolic patients with cirrhosis. Hypermetabolism had no association with clinical or biochemical data on liver function. REE correlated with total body potassium content (TBP; r = 0.49, P < 0.0001). Hypermetabolic patients had lower than normal body weight and TBP (P < 0.05). About 47% of the variance in REE could be explained by body composition whereas clinical state could maximally explain 3%. Plasma epinephrine and norepinephrine concentrations were elevated in hypermetabolic cirrhotic patients (by 56% and 41%, respectively; P < 0.001 and 0.01). Differences in REE from predicted values were positively correlated with epinephrine concentration (r = 0.462, P < 0.001). Propranolol infusion resulted in a decrease in energy expenditure (by 5 +/- 3%; P < 0.05), heart rate (by 13 +/- 4%; P < 0.01), and plasma lactate concentrations (by 32 +/- 12%; P < 0.01); these effects were more pronounced in hypermetabolic patients (by 50%, 33%, and 68%, respectively; each P < 0.05). Hypermetabolism has no association with clinical data and thus is an extrahepatic manifestation of liver disease. Increased beta-adrenergic activity may explain approximately 25% of hypermetabolism.

Regulation of aldosterone biosynthesis: the end of the road?

1. Because aldosterone is the minority hormone of the adrenal cortex, its proper function depends on protective physiological mechanisms. These include a particular site of aldosterone biosynthesis in the zona glomerulosa of the adrenal cortex as well as a complex multifactorial control system, which adapts aldosterone production to acute and chronic changes in body sodium and potassium content, irrespective of pituitary adrenocorticotropic hormone (ACTH) secretion. 2. Over the past decade, an important element of these mechanisms has been identified in the form of the enzyme involved in the final steps of aldosterone biosynthesis. In species such as the human, rat and mouse, the conversion of deoxycorticosterone to aldosterone is catalysed by an isozyme (CYP11B2) of cytochrome P450(11) beta (CYP11B1). The gene encoding this enzyme is expressed only in the zona glomerulosa. Its transcription is enhanced by sodium deficiency and potassium intake, but is suppressed by long-term administration of high doses of ACTH. 3. In contrast, the gene encoding CYP11B1 (i.e. the major (non-aldosterone-producing) type of the enzyme) is expressed mainly in the zona fasciculata and its expression depends on physiological concentrations of ACTH. 4. In other animal species (cattle, pig, sheep), the major forms of cytochrome P450(11) beta have an inherent aldosterone-synthesizing activity, which is, however, selectively suppressed in mitochondria of zona fasciculata cells. 5. The elucidation of the mechanisms involved in this suppression or of those mediating alterations in CYP11B2 expression in response to physiological stimuli may be important areas of future research on the regulation of aldosterone biosynthesis.

Effect of potassium concentration in dialysate on total body potassium

Objective: To investigate the effects of the presence/absence of potassium in the dialysate on total body potassium content in stable hemodialysis patients. Design: Randomized selection. Setting: Outpatient chronic hemodialysis unit at the James A. Haley VA Hospital in Tampa, Florida. Patients: Six adult hemodialysis patients (mean age 48 ± 11.61 years, range 32–65 years) participated in this study. They were all males, four African-Americans and two Caucasians. Intervention: Subjects in a random order received dialysis using a dialysate containing no potassium for 3 months, followed by a 2 mEq/L of potassium for another 3 months. Total body potassium measurements and routine blood analysis were taken at baseline and after each three month period. All subjects received diet instruction pre and monthly on a 3 g/day potassium dietary restriction. Main outcome measured: There were no significant differences in the amount of total body potassium concentration between the two different dialysates containing 0 or 2 mEq/L potassium. Mean values of serum albumin were significantly higher when the subjects were dialyzed on a 0 potassium bath. Conclusion: The use of dialysate containing 0 or 2 mEq/L potassium concentration does not make a significant difference with regard to total body potassium concentration and maybe advantageous for the patients in terms of more freedom in nutritional intake as demonstrated by a significant increase in serum albumin when they were dialyzed on a 0 potassium bath.

Body potassium content and radiation dose from 40K to the Slovak population.

A group of 219 subjects of Slovak adults from both sexes were studied for potassium body content by measuring the whole body activity of naturally occurring 40K using a whole body counter. The average body potassium value is 1.68 +/- 0.33 g kg(-1) body weight for males and 1.60 +/- 0.30 g kg(-1) for females. For both sexes the average body content of K was 1.62 +/- 0.30 g kg(-1). The concentration of potassium varies inversely with age. The specific activity of 40K varies inversely with slenderness. The total body potassium varies directly with body-build index for males, while its value is essentially constant for young females and tends to decrease with body-build index for old females. The average annual dose from 40K is 150 +/- 30 microGy for males and 140 +/- 30 microGy for females. For both sexes the average annual dose is 142 +/- 30 microGy. Both total potassium body content and annual dose from 40K for older subjects are below the values reported by the UNSCEAR.

Body fat estimation in late pregnancy and early postpartum: comparison of two-, three-, and four-component models

Accurate methods for determining body fat mass during reproduction are necessary to evaluate energy balance. However, determination of fat mass is complicated during pregnancy by the accretion of water, which invalidates assumptions underlying standard two-compartment models. The extent to which the variability in body water during pregnancy invalidates use of pregnancy-corrected two-compartment models for determination of fat mass in individual women is unknown. Moreover, it is unclear whether body water returns to nonpregnant values by 2 wk postpartum, which is frequently used as the baseline in studies of postpartum women. The present study uses a four-component model as a criterion for evaluating two- and three-component models. Fifty-six healthy, normotensive women between the ages of 19 and 35 y were studied at 36 +/- 1 wk gestation and 15 +/- 2 d postpartum. Total body water (TBW), total body potassium (TBK), body density, and bone mineral content were measured by deuterium dilution, whole-body potassium counting, hydrodensitometry, and dual-energy X-ray absorptiometry (postpartum only), respectively. At 2 wk postpartum, hydration and density of fat-free mass (FFM) had not returned to nonpregnant values, and differed between lactating and nonlactating women (P < 0.05). Accordingly, standard TBW and body density estimates of fat mass differed from four-component estimates at both time points (P < 0.005). Moreover, our data indicate that even when pregnancy-specific values for hydration or density of FFM are used in TBW and body density models, individual fat mass estimates may differ by > 3 kg from the four-component value. Fat mass by TBK may differ by > 10 kg from fat mass by the four-component model during pregnancy, and by 6 kg postpartum. Use of standard two-compartment models to estimate fat mass results in significant error both during pregnancy and at 2 wk postpartum. Pregnancy-corrected two-compartment models produce reliable mean fat mass estimates during pregnancy, but individual fat mass estimates may vary widely from four-component values.

The use of body water, sodium, potassium and calcium content to investigate the nutritional status of first year Atlantic salmon parr in two Scottish Highland streams

Water content of Atlantic salmon parr fell from about 84% at emergence (late May) to just under 79% in September but rose again towards March. Na+ content consequently rose from 3·3 mg g−1 dry wt at the beginning of June to 6·2 mg g−1 in early July. It then fell to 4·4 mg g−1 in September, rising again towards March. K+ content rose to a maximum in July to stabilize at 16·6 mg g−1 dry wt in September. The resultant Na+/K+ ratio peaked at 0·43: 1 in mid‐June, falling to a minimum in mid‐August but rising again in March reflecting changes in the relative proportions of intra and extracellular water. The changes in whole‐body chemistry suggest a period of nutritional stress immediately after emergence and during the winter. In streams at higher altitude and of lower nutrient status, nutritional stress during the winter appears to be more severe.

The use of body water, sodium, potassium and calcium content to investigate the nutritional status of first year Atlantic salmon parr in two Scottish Highland streams

Water content of Atlantic salmon parr fell from about 84% at emergence (late May) to just under 79% in September but rose again towards March. Na+ content consequently rose from 3·3 mg g−1 dry wt at the beginning of June to 6·2 mg g−1 in early July. It then fell to 4·4 mg g−1 in September, rising again towards March. K+ content rose to a maximum in July to stabilize at 16·6 mg g−1 dry wt in September. The resultant Na+/K+ ratio peaked at 0·43: 1 in mid-June, falling to a minimum in mid-August but rising again in March reflecting changes in the relative proportions of intra and extracellular water. The changes in whole-body chemistry suggest a period of nutritional stress immediately after emergence and during the winter. In streams at higher altitude and of lower nutrient status, nutritional stress during the winter appears to be more severe.

Body composition and two-compartment model assumptions in male long distance runners

Long distance running increases bone mineral mass, skeletal muscle weight, and extracellular fluid volume. Each of these changes may have an impact on classic two-compartment body composition methods that assume a constant fat-free body mass (FFM) density (1.100 g.cc-1), potassium content (65 mmol.kg-1 FFM), and hydration (0.73 kg H2O.kg-1 FFM). The aims of the present study were: to use newly developed multi-component methods to evaluate the validity of two-compartment methods in white male recreational long-distance runners (N = 10); and to compare the body composition of these runners to sedentary controls (N = 10) of similar age, body weight, and body mass index. Runners had a significantly smaller fraction of body weight as fat (P = 0.001) and a larger fraction of FFM as lower extremity skeletal muscle (P = 0.045) and bone (P = 0.049). Although FFM constituted a larger proportion of body weight in the runners, the fractional contributions of water, protein, and mineral were similar to those in the control group. There were no significant differences between the two groups in density of FFM, total body potassium/FFM, and total body water/FFM. New methods thus allow in-depth analyses of body composition in athletes, with results suggesting that classic two-compartment methods are valid in white recreational long-distance runners.

Biochemical and muscle studies in patients with acute onset post-viral fatigue syndrome.

To investigate in detail various biochemical and pathophysiological indices of muscle pathology in acute onset post-viral fatigue syndrome (PVFS). Twenty three patients with PVFS (of mean duration 4.6 years) were subjected to needle biopsy for histomorphometry and total RNA contents. Plasma analysis included serology and creatine kinase activities. Indices of whole body mass were also measured--namely, whole body potassium content and plasma carnosinase activities. About 80% of the patients had serology indicative of persistent enteroviral infection as determined by VP1 antigen assay. Only about 10% of that same group of patients had serological indications of current enterovirus infection by IgM assay; a separate subset of 10% showed antibody changes suggestive of reactivation of Epstein-Barr virus. Quantitative morphometric analysis of skeletal muscle fibres indicated that the quadriceps muscle was normal or displayed only minor abnormalities in 22 patients. The Quetelet's Index (body mass index) and whole-body potassium values (index of lean body mass) were not affected in PVFS. The mean plasma carnosinase and creatinine kinase activities were also generally normal in these patients. The mean muscle RNA composition--mg RNA/mg DNA: was significantly reduced in acute onset PVFS by about 15%. The protein:DNA ratio was not significantly affected. Patients with acute onset PVFS, therefore, lose muscle protein synthetic potential, but not muscle bulk. Histopathology is consistent with these observations. These perturbations may contribute to the apparent feature of perceived muscle weakness associated with the persistent viral infection in the muscle themselves.

Skeletal muscle sodium and potassium changes after successful surgery in acromegaly: relation to body composition, blood glucose, plasma insulin and blood pressure

The aim of this study was to investigate the skeletal muscle sodium/potassium (Na/K) ratio in acromegaly before and 1 year after trans-sphenoidal removal of a growth hormone (GH)-secreting pituitary adenoma. Muscle biopsies were taken and skeletal muscle electrolytes, body composition, glucose, insulin and blood pressure were studied. Fasting blood glucose and plasma insulin levels, but not blood pressure, were higher in acromegalic patients (N = 9) than in controls (N = 6). The skeletal muscle potassium content was higher (p < 0.01) but the sodium content and the Na/K ratio were lower (p < 0.05 and p < 0.001, respectively) in untreated patients with acromegaly as compared to weight-matched healthy controls. Elevated GH, glucose and insulin levels normalized after surgery. Blood pressure remained unchanged. The total body potassium content, the lean body mass and the total body water content decreased and the body fat content increased while the body weight was unchanged. The skeletal muscle potassium content decreased from [medium (range)] 9.8 (9.2-11.5) to 7.7 (5.7-9.5) mmol/100 g wet wt (p < 0.001). The skeletal muscle sodium content increased from 2.8 (2.5-3.9) to 5.1 (4.3-6.7) mmol/100 g wet wt (p < 0.001) and the Na/K ratio increased from 0.28 (0.26-0.38) to 0.56 (0.51-1.18) (p < 0.001) after surgery, which is a higher level than the controls with a Na/K ratio of 0.47 (0.39-0.84) (p < 0.01). These changes seem to be mediated by a decreased GH effect on the Na/K pump after successful trans-sphenoidal surgery in acromegaly.

Potassium requirement of fingerling channel catfish, Ictalurus puntatus

An 8-week feeding study was conducted to determine the potassium requirement of juvenile channel catfish. Six dietary levels of potassium ranging from 0.01 to 0.49% were fed to triplicate groups of catfish (initial average weight of 16.6 g) in flow-through aquaria at a water temperature of 26.7 ± 1.1 °C. The rearing water contained 4 mg/l potassium. No significant differences were observed in either weight gain or feed efficiency among the experimental groups. No dose-response relationship was apparent between dietary potassium level and whole body potassium concentration, indicating that these animals do not have a dietary requirement for potassium with potassium in the rearing water at a concentration of 4 mg/l or higher. However, when these data were used to calculate the whole body potassium balance for each group of fish it became clear that the fish do have a potassium requirement that can be met by either dietary potassium or the uptake of potassium from the rearing water. Linear regression analysis of the dietary potassium levels vs. whole body potassium balance values indicated a potassium requirement value of 0.26%. This requirement value is similar to the dietary potassium requirement of the rat, chick and young pig.

Bioelectrical impedance and zoometry for body composition analysis in domestic cats

Summary Zoometric measurements and bioelectrical impedance analysis were evaluated as methods of body composition determination in healthy cats. Zoometric and impedance measurements were taken on 22 anesthetized adult cats of various ages, genders, breeds, and body weights. The cats were then euthanatized. The bodies were processed through a tissue homogenizer and free-catch specimens were taken, freeze-dried, and analyzed for total body water, protein, fat, potassium, and ash content. Stepwise regression analysis was implemented to identify statistically significant relationships between the chemically determined dependent variables (total body water, protein, potassium, fat-free mass, fat mass, and percent body fat) and the zoometric measurements, with or without bioelectrical impedance analysis. Statistical analysis revealed high correlations between the dependent variables and the corresponding predicted values of those variables. Body weight alone was a poor predictor of body composition in these cats. On the basis of these findings, we suggest that zoometric and bioelectrical impedance measurements may serve as practical, noninvasive, simple, and accurate methods for estimating body composition in domestic cats.

Effects of potassium levels over the range occurring in host plants on the growth of an insect herbivore (Manduca sexto)

AbstractThird instar tobacco hornworms (Manduca sexta L.: Sphingidae) on low dietary potassium had a lower relative growth rate than individuals on diets with potassium concentrations reflecting those in host‐plants, due to decreased consumption rate, lower efficiencies of conversion of ingested and digested food (ECI and ECD), and a prolonged growth/feeding phase. Furthermore, these larvae, when placed on a diet with a moderate potassium concentration through the fourth stadium, ended up being smaller due to lower ECI and less biomass gained, and had a prolonged growth phase, which suggest an irreversible cost of the previous low potassium diet. Third instar hornworms on high potassium diets had lower ECI and ECD, and they had a prolonged growth phase. These individuals, when placed on a moderate potassium diet in the fourth stadium, gained less biomass, than those previously offered hostplant‐like‐potassium diets. Body potassium concentrations (% dw) at the end of the third stadium were similar among treatment groups. With increasing potassium concentrations in the diet, utilization efficiencies of potassium decreased and potassium concentrations in the frass increased. Correspondingly, water content (% fw) of the newly‐molted fourth instar larvae declined with increasing potassium, indicating a passive loss of water during potassium excretion. Low and high dietary potassium reduced survivorship of third instar larvae; fourth instar caterpillars previously fed the low potassium diet also had poor survivorship. We conclude that, within the normal range of potassium concentrations in the hostplants, caterpillar performance is largely unaffected by potassium concentration, but that potassium‐poor and potassium‐rich diets, such as those hornworms may sometimes experience, can reduce growth and survivorship.

Mineral content and blood parameters of dying brown trout ( Salmo trutta L.) exposed to acid and aluminium in soft water

1. Whole body mineral content and blood parameters were monitored in dying brown trout exposed to acid (pH 4.5) and aluminium (12μmol l −1) at low external calcium concentration (20μmol l −1). 2. Fish surviving the treatment had elevated haematocrit, low plasma sodium levels, and low whole body sodium and potassium content. 3. Dying trout had haematocrit and plasma sodium levels similar to treatment survivors, but whole body mineral content was unaffected and moisture content increased. 4. Death was probably caused by redistribution of fluid from the extracellular compartment to the intracellular compartment.

Effect of Home Total Parenteral Nutrition on Body Composition in Patients with Acquired Immunodeficiency Syndrome

Malnutrition occurs commonly in patients with acquired immunodeficiency syndrome (AIDS). The efficacy of nutritional support is unknown. A prospective, longitudinal study was conducted to determine the effect of prolonged total parenteral nutrition on body composition in 12 AIDS patients. Five patients were malnourished because of problems with food intake or absorption, while seven had systemic infections, with or without a malabsorption syndrome. The AIDS patients gained body weight and body fat content in response to total parenteral nutrition, while mean body cell mass, estimated as total body potassium content, was unchanged. However, all five patients with altered intake or absorption had significant repletion of body cell mass which was significantly different from the patients with systemic infections. Calorie and nitrogen intake did not differ between the two groups. It is concluded that body mass repletion is possible in AIDS patients in whom malabsorption is the major pathogenetic factor in producing malnutrition and is less successful in patients with serious ongoing systemic diseases. Thus, the response to nutritional support is dependent on the particular clinical circumstances.

Mechanisms for Tolerance of Sodium Loss during Exposure to Low pH of the Acid-tolerant SunfishEnneacanthus obesus

The acid-tolerant banded sunfish (Enneacanthus obesus) survived losses in body sodium, due to low pH, that would kill other species. Asplasma sodium concentration declined, aproportionate decline of plasma osmoticpressure occurred, followed by shrinkage of the extracellularfluid volume (ECFV). ECFV declined from 44% of the total body water at control pH to about 30% after 1 wk at pH 3.5. Enneacanthus obesus compensated for the lowpH-induced osmotic disturbance in several ways. With body salt depletion, sodium shifted from the slowly exchangeable pool (SEP), where it was osmotically inactive, into the rapidly exchangeable pool (REP), where it helped to maintain the extracellular fluid sodium concentration. About 88% of the total sodium in the fish at the control pH was in the REP. The proportion declined to about 81% after 2 d atpH 3.5, but returned to control levels by 14 d. Sodium in bone constitutes one-fifth of all the sodium in the fish and is an important component of the SEP. The sodium concentration of bone declined during acid exposure, which indicates that it may be a significant reservoir during depletion of body sodium. Decreases in body water content and body potassium concentration helped reduce movement of water from the extracellular fluid into the intracellular fluid. These compensatory changes took days, andpresumably accounted at leastpartially for acclimation efects on sodium balance. In contrast, the sizes of the REP and ECFV of E. obesus that died after 1–2 h at pH 2.95 increased to 100% of body sodium and 59% of body water, respectively, even though they lost no more sodium than those that were alive atpH 3.5 after 1 wk. Toxic effects of low pH involve not only the total amount of body sodium lost but also the rate at which it is lost.

Total Body Electrolyte Composition in Patients with Heart Failure

Total body elemental composition was measured in 40 patients with well documented heart failure who were oedema-free on digoxin and diuretics. The results were compared with values for 20 patients with untreated essential hypertension matched for height, weight, age, and sex. Total body potassium alone was also measured in 20 normal subjects also matched for anthropomorphic measurements. Patients with hypertension had a very similar total body potassium content to that of normal subjects, but patients with heart failure had significantly reduced total body potassium. This could not be explained by muscle wasting because total body nitrogen, largely present in muscle tissue, was well maintained. When total body potassium was expressed as a ratio of potassium to nitrogen mass a consistent depletion of potassium was revealed in the group with heart failure. Potassium depletion was poorly related to diuretic dose, severity of heart failure, age, or renal function. Activation of the renin-angiotensin-aldosterone system was, however, related to hypokalaemia and potassium depletion. Such patients also had significantly lower concentrations of serum sodium and blood pressure. Serum potassium was related directly to total body potassium. Despite the absence of clinically apparent oedema total body chlorine was not consistently increased in heart failure, but the calculated extracellular fluid volume remained expanded in the heart failure group. Total body sodium was significantly increased in patients with heart failure, but less than half of this increase could be accounted for by extracellular fluid volume expansion. Potassium depletion in heart failure may account in part for the high frequency of arrhythmias and sudden death in this condition.

Total body electrolyte composition in patients with heart failure: a comparison with normal subjects and patients with untreated hypertension.

Total body elemental composition was measured in 40 patients with well documented heart failure who were oedema-free on digoxin and diuretics. The results were compared with values for 20 patients with untreated essential hypertension matched for height, weight, age, and sex. Total body potassium alone was also measured in 20 normal subjects also matched for anthropomorphic measurements. Patients with hypertension had a very similar total body potassium content to that of normal subjects, but patients with heart failure had significantly reduced total body potassium. This could not be explained by muscle wasting because total body nitrogen, largely present in muscle tissue, was well maintained. When total body potassium was expressed as a ratio of potassium to nitrogen mass a consistent depletion of potassium was revealed in the group with heart failure. Potassium depletion was poorly related to diuretic dose, severity of heart failure, age, or renal function. Activation of the renin-angiotensin-aldosterone system was, however, related to hypokalaemia and potassium depletion. Such patients also had significantly lower concentrations of serum sodium and blood pressure. Serum potassium was related directly to total body potassium. Despite the absence of clinically apparent oedema total body chlorine was not consistently increased in heart failure, but the calculated extracellular fluid volume remained expanded in the heart failure group. Total body sodium was significantly increased in patients with heart failure, but less than half of this increase could be accounted for by extracellular fluid volume expansion. Potassium depletion in heart failure may account in part for the high frequency of arrhythmias and sudden death in this condition.

Adaptations of sodium balance to low pH in a sunfish (Enneacanthus obesus) from naturally acidic waters

Net sodium flux (Jnet), sodium influx (Jin), and sodium efflux (Jout) were measured in two sunfish,Enneacanthus obesus (acid-tolerant) andLepomis gibbosus (less acid-tolerant), during 24 h exposure to soft water of pH's 4.0 and 3.5.E. obesus exhibited a mild transitory disturbance at both pH's caused by inhibitedJin and slightly stimulatedJout. Body and plasma ion concentrations ofE. obesus were measured weekly during exposures for 5 weeks to acidified artificial soft water (ASW). Body sodium concentration declined 30% during 2 weeks exposure to pH 3.5 but no further during the next three weeks. Exposure to pH 4.0 had no effect on body sodium concentration during the entire 5 weeks. Plasma sodium concentration declined 15% over a 3 week period at pH 3.5; there was no further change in the next two weeks. Plasma potassium concentrations, which were measured after 4 and 5 weeks at pH's 5.8 and 3.5 in ASW, were not significantly different. In a separate two week long experiment, plasma sodium concentration ofE. obesus in ASW was correlated with pH between pH's 3.5 and 7.5. This effect was mainly due to increases above pretreatment levels at pH 4.5 and above. Increased ambient sodium and calcium concentrations had no effect on body sodium concentration ofE. obesus at pH 5.8, but mitigated the effects of exposure to pH 3.5. Increased calcium concentrations up to 25 μM at pH 3.5 increased body sodium concentration, but higher concentrations had no additional effect. Body potassium concentration and body water concentration ofE. obesus were linearly related to body sodium concentration under a wide variety of external conditions. This suggests the presence of a mechanism by whichE. obesus regulates plasma sodium levels and body fluid compartments in response to sodium loss. In contrast toE. obesus, L. gibbosus showed larger sodium losses at low pH resulting from greater acceleration ofJout; those exposed at pH 3.5 died in less than 12 h.L. gibbosus also had reduced body and plasma sodium concentrations at pH 4.5 and below; those at pH 4.0 were the lowest. Body potassium concentration ofL. gibbosus was reduced in those fish exposed to pH 4.0 and below, but body water was increased. Thus there are striking differences in the ability to regulate ion and water balance at low pH between an acid-tolerant specialist (E. obesus) and a less acid-tolerant generalist (L. gibbosus).

Total body potassium, intracellular potassium and body composition in patients with anorexia nervosa during refeeding

The total body potassium content and the potassium concentration in serum and erythrocytes was measured in 16 patient with anorexia nervosa (8 “vomiters” and 8 “restricters”). The data were compared with results obtained for 11 normal controls, whose body weight was 99.6% ± 4.99% of ideal body weight (IBW). Patients were studied before treatment (IBW 72.8 ± 6.3%) and after an average weight gain of 19%. Serum potassium was not significantly different between groups, but potassium concentration was significantly reduced (p < 0.01) in both groups at the time of the first study. Total body potassium—as measured by the potassium-40 method—was significantly lower in both “vomiters” and “restricters” than in controls and was normalized during weight gain. Cell body mass and fat mass were calculated from the potassium-40 measurement. Both body compartments were significantly increased during weight gain; cell mass was normalized, but fat mass remained significantly below normal values.