Zinc finger protein 5 (ZFP5) associates with ethylene signaling to regulate the phosphate and potassium deficiency-induced root hair development in Arabidopsis

Zinc finger protein transcription factor ZFP5 positively regulates root hair elongation in response to Pi and potassium deficiency by mainly activating the expression of EIN2 in Arabidopsis. Phosphate (Pi) and potassium (K⁺) are major plant nutrients required for plant growth and development, and plants respond to low-nutrient conditions via metabolic and morphology changes. The C2H2 transcription factor ZFP5 is a key regulator of trichome and root hair development in Arabidopsis. However, its role in regulating root hair development under nutrient deprivations remains unknown. Here, we show that Pi and potassium deficiency could not restore the short root hair phenotype of zfp5 mutant and ZFP5 RNAi lines to wild type level. The deprivation of either of these nutrients also induced the expression of ZFP5 and the activity of an ethylene reporter, pEBS:GUS. The significant reduction of root hair length in ein2-1 and ein3-1 as compared to wild-type under Pi and potassium deficiency supports the involvement of ethylene in root hair elongation. Furthermore, the application of 1-aminocyclopropane-1-carboxylic acid (ACC) significantly enhanced the expression level of ZFP5 while the application of 2-aminoethoxyvinyl glycine (AVG) had the opposite effect when either Pi or potassium was deprived. Further experiments reveal that ZFP5 mainly regulates transcription of ETHYLENE INSENSITIVE 2 (EIN2) to control deficiency-mediated root hair development through ethylene signaling. Generally, these results suggest that ZFP5 regulates root hair elongation by interacting with ethylene signaling mainly through regulates the expression of EIN2 in response to Pi and potassium deficiency in Arabidopsis.

Nonadherence to potassium replacement protocol leads to prolonged management of diabetic ketoacidosis

Introduction Diabetic ketoacidosis is a life-threatening condition that requires prompt management. Objectives We aimed to assess the impact of adherence to potassium replacement protocol according to the guidelines of Diabetes Poland on the duration of diabetic ketoacidosis (DKA) treatment. Patients and methods This retrospective analysis included 242 adults (median age, 27 years; range, 21-38 years). Nonadherence to potassium replacement protocol was assessed, along with the relationship between nonadherence and duration of DKA management. Nonadherence to the protocol was defined as too low or too high doses of potassium compared with the recommended potassium replacement protocol. Results The median duration of DKA treatment was longer in the nonadherent group than in the adherent group: 37 hours (interquartile range [IQR], 27-48) and 30 hours (IQR, 17-43), respectively (P = 0.005). Treatment duration correlated positively with nonadherence to potassium replacement protocol (r = 0.18; P = 0.005) and severity of DKA (r = 0.52; P <0.0001). Stepwise multivariate linear regression analysis indicated nonadherence to the protocol (β = 0.14; P = 0.02) and severity of DKA (β = 0.43; P <0.0001) as predictors of treatment duration, after adjustment for body mass index and age (R2 = 0.28; P <0.0001). Conclusions Nonadherence to potassium replacement protocol leads to prolongation of DKA management. Medical staff should be educated about the benefits of potassium replacement and precision in potassium administration and dosing in patients with DKA.

[Potassium magnesium homeostasis: physiology, pathophysiology, clinical consequences of deficiency and pharmacological correction]

The metabolism of K and Mg is closely linked. Mg deficiency may arise together with and contribute to the persistence of K deficiency. Isolated disturbances of K balance do not produce secondary abnormalities in Mg homeostasis. In contrast, primary disturbances in Mg balance, particularly Mg depletion, produce secondary K depletion. This appears to result from an inability of the cell to maintain the normally high intracellular concentration of K, perhaps as a result of an increase in membrane permeability to K and / or inhibition of Na+-K+-ATPase. Cases of Mg deficiency accompanying with Mg-dependent or -independent K deficiency are not uncommon among the general population. K and Mg deficiencies are found in patients with chronic alcoholism, cardiac diseases, diabetes mellitus (type II), genetic forms of renal potassium and magnesium wasting (Gitelman's and Bartter's syndromes), severe diarrhea and vomiting, malnutrition, during therapy with some kind of drugs. Various K-Mg salts allowing simultaneously eliminating deficiency of Mg and K are described in the literature. K-Mg aspartate is most distributed among K-Mg salts. It can be used as adjuvant therapy in ischaemic heart disease (in angina pectoris and conditions after myocardial infarction), prophylaxis and adjuvant therapy of cardiac arrhythmia (e.g. prevention of toxic symptoms during therapy with digoxin). Differences in metabolism and utilisation of D- and L-amino acids probably may effect on pharmacological properties of K-Mg L- and D-aspartates, and what is more pharmacological doses of Mg and K salts may induce toxicity which differs according to the nature of the anions. In our research it was established, that L-aspartate salts are better delivery forms for cations such as Mg and K than D-aspartate salts. K-Mg L-aspartate can be more beneficial in the treatment of several forms of primary Mg and K deficiency than K-Mg DL-aspartate and K-Mg D-aspartate.

Cesium chloride protects cerebellar granule neurons from apoptosis induced by low potassium

Neuronal apoptosis plays a critical role in the pathogenesis of neurodegenerative disorders, and neuroprotective agents targeting apoptotic signaling could have therapeutic use. Here we report that cesium chloride, an alternative medicine in treating radiological poison and cancer, has neuroprotective actions. Serum and potassium deprivation induced cerebellar granule neurons to undergo apoptosis, which correlated with the activation of caspase-3. Cesium prevented both the activation of caspase-3 and neuronal apoptosis in a dose-dependent manner. Cesium at 8 mM increased the survival of neurons from 45 +/- 3% to 91 +/- 5% of control. Cesium's neuroprotection was not mediated by PI3/Akt or MAPK signaling pathways, since it was unable to activate either Akt or MAPK by phosphorylation. In addition, specific inhibitors of PI3 kinase and MAP kinase did not block cesium's neuroprotective effects. On the other hand, cesium inactivated GSK3beta by phosphorylation of serine-9 and GSK3beta-specific inhibitor SB415286 prevented neuronal apoptosis. These data indicate that cesium's neuroprotection is likely via inactivating GSK3beta. Furthermore, cesium also prevented H(2)O(2)-induced neuronal death (increased the survival of neurons from 72 +/- 4% to 89 +/- 3% of control). Given its relative safety and good penetration of the brain blood barrier, our findings support the potential therapeutic use of cesium in neurodegenerative diseases.

Potassium and magnesium depletions in congestive heart failure--pathophysiology, consequences and replenishment

Congestive heart failure (CHF) is becoming more frequent worldwide. Both potassium (K) and magnesium (Mg) deficiencies are common and can be associated with risk factors and complications of heart failure (HF). The major causes of K and Mg depletions are the effects of compensatory neuroendocrine mechanisms (activation of the renin-angiotensin-aldosterone and sympathoadrenergic systems), digoxin therapy, and administration of thiazide or loop diuretic therapy in CHF. Particular attention should be paid to K and Mg restoration in CHF, because of the consequences of both deficiencies (increased arrhythmic risk, vasoconstriction), and the co-supplementation of both ions is necessary in order to achieve K repletion. Mg and K should be employed as first-line therapy in digitalis intoxication and drug-related arrhythmias, and should be considered an important adjuvant therapy in diuretic treated patients with CHF. Another possibility to restore normal K and Mg status is usage of a K, Mg sparing diuretics.

A primary Sjögren’s syndrome patient with distal renal tubular acidosis, who presented with symptoms of hypokalemic periodic paralysis

Although renal tubular acidosis (RTA), secondary to autoimmune interstitial nephritis, develops in a large proportion of patients with Sjögren's syndrome (SS), most of the subjects are asymptomatic. Here, we shall present a 39-year-old female patient who came to us with hypokalemic periodic paralysis (HPP), and who was later diagnosed with distal RTA. The patient, who had xerostomia and xerophthalmia for a long period of time, was diagnosed with primary SS from serologic and histologic findings. The patient recovered by being prescribed potassium replacement therapy. Although renal biopsy was not performed, corticosteroids were administered because HPP indicated severe interstitial nephritis. HPP did not reoccur during a 2-year follow-up period. We also review cases with SS-related distal RTA and HPP.

In vivo 31P-MRS assessment of muscle-pH, cytolsolic-[Mg2+] and phosphorylation potential after supplementing hypokaliuric renal stone patients with potassium and magnesium salts

Renal stone patients in rural northeast Thailand have a low potassium and magnesium status and low urinary excretion of citrate. We measured the changes of urinary citrate excretion and assessed in vivo skeletal muscle metabolism for intracellular-pH, cytosolic-[Mg(2+)] and phosphorylation potential (using the phosphorus magnetic resonance spectroscopy (31)P-MRS) after oral supplementation to hypokaliuric renal stone patients with oral potassium and magnesium salts. The patients comprised four groups: Group 1 (n = 10) control, Group 2 (n = 3), Group 3 (n = 5) and Group 4 (n = 6) supplemented for a month with potassium citrate, potassium citrate plus amino acid chelated magnesium, and potassium-magnesium citrate, respectively. Though urinary citrate excretion was increased in all three supplemented groups, the increases in intracellular-pH, cytosolic-[Mg(2+)] and phosphocreatine (PCr)/beta-ATP were prominent only in Group 3. The increase in PCr/beta-ATP was also observed in Group 4.

Thyrotoxic periodic paralysis: an unusual presentation of weakness

Thyrotoxic periodic paralysis is a rare endocrine disorder seen predominantly in men of Asian origin. The case is reported of a patient who presented to the accident and emergency department with sudden onset of weakness of his lower limbs. Hypokalaemia was identified and treated with resolution of symptoms. Additional tests identified the patient as being thyrotoxic. He was treated with oral antithyroid drugs. It is important to consider the diagnosis of thyrotoxic periodic paralysis in patients presenting with acute onset of weakness. The report discusses the epidemiology, presentation, treatment, and complications of this condition.

[Therapy of cardiac arrhythmias. Clinical significance of potassium- and magnesium aspartate in arrhythmias]

Potassium and magnesium deficiencies usually coexist and represent a risk factor for cardiac arrhythmias. Serum levels--in particular of magnesium--are inconclusive for establishing a possible electrolyte deficiency. Basic treatment of arrhythmia should therefore include the administration of potassium and magnesium, since the benefit is great, and the possible side effects is negligible. A placebo-controlled study involving patients with cardiac arrhythmias revealed that appreciably fewer ventricular asystoles occurred after three weeks of treatment with potassium and magnesium aspartate, even when serum levels were within the normal range prior to initiating treatment. Patients older than 50, and those with previous coronary heart disease and/or myocardial infarction derived particular benefit from this form of treatment.

CONCLUSION

These results underscore the key role played by potassium and magnesium in the treatment of cardiac arrhythmias.

The effects of potassium depletion and supplementation on blood pressure: a clinical review

Nonpharmacologic treatment currently is recognized as an important part in the treatment of hypertension, and the role of dietary potassium intake in blood pressure (BP) control is becoming quite evident. Clinical studies have examined the mechanism by which hypokalemia can increase BP and the benefit of a large potassium intake on BP control. Epidemiologic data suggest that potassium intake and BP are correlated inversely. In normotensive subjects, those who are salt sensitive or who have a family history of hypertension appear to benefit most from the hypotensive effects of potassium supplementation. The greatest hypotensive effect of potassium supplementation occurs in patients with severe hypertension. This effect is pronounced with prolonged potassium supplementation. The antihypertensive effect of increased potassium intake appears to be mediated by several factors, which include enhancing natriuresis, modulating baroreflex sensitivity, direct vasodilation, or lowering cardiovascular reactivity to norepinephrine or angiotensin II. Potassium repletion in patients with diuretic-induced hypokalemia improves BP control. An increase in potassium intake should be included in the nonpharmacologic management of patients with uncomplicated hypertension.

[Heart rate disorders in potassium and magnesium deficiency]

Potassium and magnesium deficiencies are common in patients with heart disease. These are often coexistent and pathophysiologically related. Potassium deficiency cannot be treated without correction of concomitant magnesium deficiency. Correlations between serum levels and body stores are very poor for both ions. Therefore diagnosis and treatment of these conditions based on serum levels alone are erroneous. There is some evidence that it is primarily the intracellular depletion of these ions which is arrhythmogenic. Magnesium infusion has been proved effective in treatment of torsade de pointes ventricular tachycardia and arrhythmias induced by digoxin-intoxication, and is recommended in these conditions. Whether it is effective in other forms of arrhythmia is not yet elucidated.

Recovery of heart tissue following focal injury induced by dietary restriction of potassium

Sixty-four Sprague-Dawley rats (initially weighing 200-225 grams) were divided into three groups. Group 1, the experimental group, was fed a potassium depleted diet for 42 days, followed by a potassium repleted diet for up to an additional 14 days. Group 2, the dietary control group, received a potassium deficient diet, but was continuously supplemented by drinking water containing potassium chloride 150 meq/L. Group 3, the control group remained on normal rat chow and tap water during the entire investigation. Quantitative morphometric analysis was used to assess the percent of myocardium occupied by lesion. These data were analyzed by an analysis of variance (ANOVA) for repeated measures, comparing the three groups with one another; a second analysis compared the myocardial lesions of the dietary experimental group during the potassium depletion and repletion periods. At the end of the dietary depletion period (day 42) focal areas of cardiac myocyte necrosis and mononuclear infiltrate were found in the experimental group. Morphometric assessment on day 42 revealed a volume fraction (Vv) of 8.61 (+/- 4.41)%, which was significantly greater (p = 0.0018), as compared with both control groups. Lesion area significantly regressed in two and one half days after potassium was supplemented in the dietary experimental group to 0.58 (+/- 0.34)% Vv (p = 0.0005). Six days after potassium was replaced in the diet, there was no significant difference between the experimental and control groups, and only a limited connective tissue scar was noted in the experimental group. The mechanism of the rapid regression of lesions and the production of only limited connective tissue scar is suggested but requires further elucidation.

Current approaches to management of potassium deficiency

Current issues related to oral potassium supplementation are reviewed, with emphasis on recommendations for the appropriate use of potassium supplementation for both replacement and preventive therapy. Dietary potassium intake, potassium-sparing diuretics, and the various forms of oral potassium supplements are reviewed in terms of indications for use, advantages, and limitations. Attention is given to controversial areas, i.e., gastrointestinal tolerance of controlled-release potassium oral dosage preparations and the need for potassium supplementation in hypertensive patients treated with diuretics.

Serum potassium levels, red-blood-cell potassium and alterations of the repolarization phase of electrocardiography in old subjects

Seventeen elderly patients are described, who showed minor changes in the e.c.g. recovery phase. Serum potassium levels appeared to be normal, but red-blood-cell potassium was found to be more or less markedly reduced. Restoration of the latter to normal values, which followed treatment with potassium salts was also associated with normalization of the e.c.g. pattern. These observations demonstrate that electrolyte disorders, and particularly hypokalaemia, may determine 'minor' alterations of repolarization much more frequently than is usually thought, and that determination of serum potassium levels is not a reliable tool for detecting potassium depletion, which is more accurately reflected by red-blood-cell potassium concentration.

Ultrastructural changes in the renal papillary cells of rats during maintenance and repair of profound potassium depletion

In rats with long-term diet-induced potassium depletion, the cytoplasm of markedly enlarged papillary cells was mainly occupied by membrane-bound droplets, many of which acquired massive proportions. Both free and attached ribosomes were decreased, the Golgi apparatus was inconspicuous and there was a paucity of mitochondria. Despite the overwhelming accumulation of droplets with concomitant loss of normal metabolic organelles, cell death did not occur. With potassium repletion, the organelles readily proliferated regardless of the progression of droplet dissolution. The shrinkage of the droplets was accompanied either by disintegration of the limiting membrane or by disappearance of the constituents within an intact membrane. Microtubules were conspicuous in many of the cells undergoing gradual reduction in size. These cytoplasmic changes in renal medullary cells of rats during long-term potassium depletion and immediate post-repletion periods essentially represented the consequences of maintenance and repair of a storage process.

The potassium status of patients prior to open-heart surgery

The dysrhythmia that happens after open-heart surgery has at times been attributed to potassium depletion. Therefore, in some centers, patients scheduled for open-heart surgery are routinely given potassium supplements. We have assessed the potassium status of 32 patients prior to cardiac surgery (1) by measurements of plasma, red cell, and leukocyte potassium levels and total body potassium before and after administration of potassium supplements (144 mmoles daily for 3 days) and (2) by the changes in urine potassium during the supplementation. On admission none of the patients showed evidence of a large potassium deficit, and none of them retained much of the supplemental potassium. The observations that have previously been taken as evidence of potassium depletion in such patients are discussed, and alternative explanations are suggested for all these observations.

The effects of potassium supplements, spironolactone of amiloride on the potassium status of patients with heart failure

Extra potassium supplements, spironolactone or amiloride were given for 5 months to forty-nine patients with heart failure who were taking furosemide and were in a steady state. Plasma potassium increased with all three treatments but there was no significant increase in total body potassium or red cell potassium. These findings together with other studies suggest that patients with heart failure taking diuretics do not have a significant depletion of body potassium.

Pharmacokinetics and effects on fecal blood loss of a controlled release potassium chloride tablet

A slow-release tablet containing 12.5 mEq of potassium chloride was compared with a potassium chloride solution in normal human subjects under controlled conditions. Changes in plasma potassium concentration and rates of urinary potassium excretion indicate the tablet is absorbed in a slow, sustained fashion in contrast to the solution. Net potassium excretion after single and multiple doses indicates that the amount of potassium absorbed from the slow-release tablet is comparable to the solution. The slow-release potassium chloride tablets were well tolerated and were effective in correcting experimentally induced potassium depletion of moderate severity. Gastrointestinal tract irritation was not apparent and fecal 51Cr red blood cell loss after the tablet and the solution were of the same order.

Potassium homeostasis

Potassium balance is regulated by appropriate changes in potassium excretion in the distal portion of the nephron. By contrast, potassium intake, absorption and proximal renal reabsorption do not show regulatory variation. Extracellular potassium concentration, which is a critical factor in membrane polarization, may at times vary in a direction opposite to total body content, because of altered distribution across cell membranes. Alterations in acid-base status frequently disturb homeostasis by altering potassium movement into cells, while insulin has an important regulatory effect on distribution. In general, the multiple renal and extra-renal mechanisms which prevent potassium overload are highly developed, while conservation is relatively ineffective. Consequently, depletion occurs more easily than spontaneous potassium overload. Homeostasis can be disturbed by renal impairment, excessive tissue breakdown, disturbances of acid-base balance, abnormal routes of loss, mineralocorticoid abnormalities and aberrations of sodium balance.

Improvement in lacrimal and salivary secretions after alkali therapy in Sjøgren's syndrome with renal tubular acidosis

A patient with Sjøgren's syndrome developed renal tubular acidosis which led to systemic acidosis and potassium depletion. Treatment with Shohl's solution and potassium supplements was followed by subjective improvement in tear flow, salivary flow, and by disappearance of bronchitic symptoms. Detailed objective assessments were then made during the next year, twice on treatment and twice without. These confirmed the subjective impression of improvement.

Dietary potassium deficiency in the elderly: a controlled trial

A controlled cross-over trial of supplementary potassium was conducted in 46 elderly people whose dietary intake of potassium appeared to be no more than 45 mEq per day. Their grip strength and mental function were no better after two weeks' treatment with 48 mEq than when they received placebo tablets. It was concluded that the possible benefits of widespread potassium supplementation do not justify the risks which would be incurred.

Potassium supplements in patients treated with corticosteroids

1. Preliminary studies are reported on 8 patients with lung disease given prednisone both with and without potassium supplements. 2. There were no abnormalities of plasma potassium but there was a relationship between the dose of prednisone and the urinary excretion of potassium whilst off supplements: higher doses were associated with increased potassium excretion. 3. Patients who had been on treatment for a short period retained more of their supplements than did those who had been on treatment for several years. 4. It is suggested that with prolonged treatment control of potassium homeostasis may be altered, and that more detailed metabolic studies should be carried out.

Total body potassium, potassium retention and potassium intake in protein energy malnutrition

The total body potassium (TBK) and potassium retention were measured during the early stages of recovery of malnourished children on three levels of potassium intake. A potassium intake of 2 mEq/kg/day resulted in significantly greater potassium retention than one of 3 mEq/kg/day. A higher level of intake (15 mEq/kg/day) did not result in an absolute increase in potassium retention and is not recommended because of its theoretical dangers, although it may have stimulated an increase in potassium capacity.