Plasma Potassium Concentration Research Articles

Plasma potassium, diuretic use and risk of developing chronic kidney disease in a predominantly White population.

ObjectiveBoth hypokalemia and hyperkalemia are associated with disease progression in patients with chronic kidney disease (CKD). It is unclear whether similar associations are present in the general population. Our aim was to examine the association of plasma potassium with risk of developing CKD and the role of diuretics in this association in a population-based cohort.Research design and methodsWe studied 5,130 subjects free of CKD at baseline of the Prevention of Renal and Vascular End-Stage Disease (PREVEND) study, a prospective, population-based cohort of Dutch men and women aged 28–75 years. Hypokalemia was defined as plasma potassium <3.5 mmol/L, and hyperkalemia as plasma potassium ≥5.0 mmol/L. Risk of CKD was defined as de novo development of eGFR <60 ml/min/1.73m2 and/or albuminuria >30 mg/24h.ResultsMean baseline plasma potassium was 4.4±0.3 mmol/L. The prevalences of hypokalemia and hyperkalemia were 0.5% and 3.8%, respectively; 3.0% of the subjects used diuretics. During a median follow-up of 10.3 years (interquartile range: 6.3–11.4 years), 753 subjects developed CKD. The potassium-CKD association was modified by diuretic use (Pinteraction = 0.02). Both hypokalemia without (HR, 7.74, 95% CI, 3.43–17.48) or with diuretic use (HR, 4.32, 95% CI, 1.77–10.51) were associated with an increased CKD risk as compared to plasma potassium 4.0–4.4 mmol/L without diuretic use. Plasma potassium concentrations ≥3.5 mmol/L were associated with an increased CKD risk among subjects using diuretics (Ptrend = 0.01) but not among subjects not using diuretics (Ptrend = 0.74).ConclusionIn this population-based cohort, hypokalemia was associated with an increased CKD risk, regardless of diuretic use. In the absence of hypokalemia, plasma potassium was not associated with an increased CKD risk, except among subjects using diuretics.

Glucocorticoid-induced leucine zipper protein regulates sodium and potassium balance in the distal nephron

Glucocorticoid induced leucine zipper protein (GILZ) is analdosterone-regulated protein that controls sodium transport in cultured kidney epithelial cells. Mice lacking GILZ have been reported previously to have electrolyte abnormalities. However, the mechanistic basis has not been explored. Here we provide evidence supporting a role for GILZ in modulating the balance of renal sodium and potassium excretion by regulating the sodium-chloride cotransporter (NCC) activity in the distal nephron. Gilz-/- mice have a higher plasma potassium concentration and lower fractional excretion of potassium than wild type mice. Furthermore, knockout mice are more sensitive to NCC inhibition by thiazides than are the wild type mice, and their phosphorylated NCC expression is higher. Despite increased NCC activity, knockout mice do not have higher blood pressure than wild type mice. However, during sodium deprivation, knockout mice come into sodium balance more quickly, than do the wild type, without a significant increase in plasma renin activity. Upon prolonged sodium restriction, knockout mice develop frank hyperkalemia. Finally, in HEK293T cells, exogenous GILZ inhibits NCC activity at least in part by inhibiting SPAK phosphorylation. Thus, GILZ promotes potassium secretion by inhibiting NCC and enhancing distal sodium delivery to the epithelial sodium channel. Additionally, Gilz-/- mice have features resembling familial hyperkalemic hypertension, a human disorder that manifests with hyperkalemia associated variably with hypertension.

Potassium Sensing by Renal Distal Tubules Requires Kir4.1.

The mammalian distal convoluted tubule (DCT) makes an important contribution to potassium homeostasis by modulating NaCl transport. The thiazide-sensitive Na+/Cl- cotransporter (NCC) is activated by low potassium intake and by hypokalemia. Coupled with suppression of aldosterone secretion, activation of NCC helps to retain potassium by increasing electroneutral NaCl reabsorption, therefore reducing Na+/K+ exchange. Yet the mechanisms by which DCT cells sense plasma potassium concentration and transmit the information to the apical membrane are not clear. Here, we tested the hypothesis that the potassium channel Kir4.1 is the potassium sensor of DCT cells. We generated mice in which Kir4.1 could be deleted in the kidney after the mice are fully developed. Deletion of Kir4.1 in these mice led to moderate salt wasting, low BP, and profound potassium wasting. Basolateral membranes of DCT cells were depolarized, nearly devoid of conductive potassium transport, and unresponsive to plasma potassium concentration. Although renal WNK4 abundance increased after Kir4.1 deletion, NCC abundance and function decreased, suggesting that membrane depolarization uncouples WNK kinases from NCC. Together, these results indicate that Kir4.1 mediates potassium sensing by DCT cells and couples this signal to apical transport processes.

Diagnosis and treatment of hyperkalemia.

Hyperkalemia results either from the shift of potassium out of cells or from abnormal renal potassium excretion. Cell shift leads to transient increases in the plasma potassium concentration, whereas decreased renal excretion of potassium leads to sustained hyperkalemia. Impairments in renal potassium excretion can be the result of reduced sodium delivery to the distal nephron, decreased mineralocorticoid level or activity, or abnormalities in the cortical collecting duct. In some instances, all 3 of these perturbations are present. Excessive intake of potassium can cause hyperkalemia but usually in the setting of impaired renal function. We discuss the clinical manifestations of hyperkalemia and outline an approach to its diagnosis and treatment.

Physiological response and immediate mortality of gill-net-caught blacktip reef sharks (Carcharhinus melanopterus)

To investigate factors contributing to immediate mortality in gill-net-caught elasmobranchs, we caught and blood sampled a total of 64 sharks and rays. Blacktip reef sharks (Carcharhinus melanopterus) were the most commonly caught species and had significantly elevated plasma lactate (mean 23.3 mM) and potassium (mean 6.2 mM) concentrations following capture, suggesting physiological disturbance. The overall immediate mortality rate of C. melanopterus was 38% and mortality was significantly influenced by body size, but not location of entanglement or sex. Of the other species caught, nervous sharks (Carcharhinus cautus) were of particular concern, because this species is often caught as bycatch by gill-net fisheries throughout its range and experienced high immediate mortality rates when captured (66%; n = 12) in the present study. The results suggest that juvenile C. melanopterus are particularly susceptible to gill-net-related mortality and that fisheries management strategies for C. melanopterus bycatch should focus on reducing the likelihood of juvenile sharks encountering this gear. Given that this species is not currently considered to be threatened with extinction, population monitoring should be performed such that the suggested regulations can be implemented if populations decline to levels threatening the conservation status of the species.

CORRELATION BETWEEN BLOOD PRESSURE AND PLASMA MONOVALENT CATIONS AND THEIR RENAL EXCRETION IN HYPERTENSIVE PATIENTS AT PSYCHOEMOTIONAL STRESS

Objective . To study the impact of psycho-emotional stress (PES) on the correlation between blood pressure (BP) and plasma sodium and potassium ions, and their renal excretion in patients with arterial hypertension (HTN). Design and methods. We examined 18 men with normal BP and 20 men with HTN of the second stage (mean age in both groups — 57 ± 3 years) who were exposed to PES. All the subjects responded by the increase in BP, pulse, diuresis, natriuresis, renal excretion of K+, clearance from Na+-CNa+. We evaluated Na+ and K+ by the flame photometer Flafo-40 (Germany), and the activity of plasma Na+ and K+ by potentiometric method with ion-selective minielectrodes ISE-M-K and the ISE-M-Na. Results. At PES, neither normotensives nor HTN patients showed any correlation between BP and either plasma sodium ions or their renal excretion. BP correlated negatively only with renal excretion of potassium ions in normotensives: the higher systolic (SBP) and diastolic (DBP) BP at all stages of the experiment (5 ties: –0,57, –0,52, –0,64, –0,56, –0,54) the lower renal excretion of potassium after PES. Normotensive subjects showed no correlation between BP and plasma potassium ions. Unlike the normotensive subjects, patients with HTN had no correlation between BP and renal excretion of potassium ions. However, patients with HTN showed negative correlation between BP (especially systolic) and plasma potassium ions: the higher SBP at baseline and at PES exposure (–0,42, –0,51), the lower the baseline concentration of plasma potassium. The higher SBP at all three stages of the experiment, the lower active potassium at baseline and at PES exposure (5 relations: –0,52, –0,45, –0,46, –0,53, –0,48). The higher SBP and DBP during and after PES exposure, the lower the coefficient of activity of potassium at PES (4 relations, –0,58, –0,47, –0,58, –0,45). Conclusions. 1) Correlation between BP and plasma sodium ions and renal sodium excretion was absent in both normotensives and HTN patients at PES exposure. 2) BP elevation negatively correlated with the renal excretion of potassium ions in normotensive subjects during PES exposure. 3) BP increase negatively correlated with the plasma potassium ions (potassium ions, active potassium and its coefficient of activity) in hypertensive patients during the PES. 4) In normotensive subjects BP negatively correlated only with the renal excretion of potassium ions during the PES. In HTN patients BP correlated negatively only with potassium ions, active potassium and potassium coefficient of activity. 5) Potassium ions play a significant role in the BP regulation and the mechanisms are different in normotensive and hypertensive individuals.

Alibertia edulis (L.C. Rich.) A.C. Rich – A potent diuretic arising from Brazilian indigenous species

Ethnopharmacological relevanceAlthough Alibertia edulis (L.C. Rich.) A.C. Rich decoction is used in Brazilian folk medicine due to its possible antihypertensive effect, this species has never been critically investigated as a hypotensive drug. So, the aim of this study was to evaluate the possible hypotensive and antihypertensive effects of the oral administration of Alibertia edulis aqueous extract (AEAE) in normotensive and hypertensive rats, and evaluate its inter-relation with a possible diuretic activity. Material and methodsDifferent doses of AEAE (20, 65 and 200mg/kg) were tested on the mean arterial pressure (MAP) of normotensive Wistar rats and after induction of renovascular hypertension (two-kidney, one-clip Goldblatt model). In addition, the diuretic effects of AEAE were compared with hydrochlorothiazide (HCTZ) in an acute and repeated-dose treatment for 7 days. Volume, sodium, potassium, chloride, calcium contents, pH and density were estimated in urine samples collected after 8 or 24h. Plasma sodium, potassium, total protein, urea, creatinine, AST and ALT concentrations were measured in samples collected at the end of the experimental period (seventh day). Finally, the antioxidant activity of the AEAE was assessed using the DPPH radical scavenging and ferric ions reducing power assay. ResultsThe intraduodenal administration of the HCTZ and AEAE significantly reduced, in a dose-dependent manner, the MAP in both normotensive and hypertensive rats. Otherwise, the heart rate was not affected by any treatment. Acute and prolonged oral administration of AEAE (200mg/kg) and HCTZ caused a significant increase in volume and urinary concentrations of sodium, potassium and chloride. Moreover, urinary calcium concentration was significantly increased after administration of AEAE (200mg/kg). Finally, AEAE was able to present important in vitro antioxidant properties. ConclusionThe results obtained have shown that AEAE presents potent diuretic activity and significant hypotensive and antihypertensive effect. In addition, this study may confirm part of the pharmacological activity popularly attributed to this species and opens perspective for the future use in various renal and cardiovascular diseases.

Physiological and molecular responses of juvenile shortnose sturgeon (Acipenser brevirostrum) to thermal stress

The shortnose sturgeon (Acipenser brevirostrum LeSueur, 1818) is a vulnerable species that is found along the eastern coast of North America. Little is known about temperature tolerance in this species and with a rapidly changing global climate, it becomes increasingly important to define the thermal tolerance of this species to better predict population distribution. Using a modified critical thermal maximum test (CTMax), the objectives of this study were to determine the impact of heating rate (0.1, 0.2 and 0.25°Cmin−1) on the thermal tolerance, associated hematological responses, and oxygen consumption in juvenile sturgeon. In addition, transcripts associated with physiological stress and heat shock (i.e., heat shock proteins) were also measured. Heating rate did not alter the CTMax values of shortnose sturgeon. Neither heating rate nor thermal stress affected plasma sodium and chloride levels, nor the expression of transcripts that included catalase, glucocorticoid receptor, heat shock protein70 (hsp70), heat shock protein 90α (hsp90α) and cytochrome P450 1a (cyp1a). However, regardless of heating rate, thermal stress increased both plasma potassium and lactate concentrations. Glucose levels were increased at heating rates of 0.2 and 0.25°Cmin−1, but not at 0.1°Cmin−1. Overall, oxygen consumption rates increased with thermal stress, but the response patterns were not affected by heating rate. These data support the hypothesis that shortnose sturgeon can tolerate acute heat stress, as many physiological and molecular parameters measured here were non-responsive to the thermal stress.

Effect of some minerals in soil and forage on same minerals in cattle plasma at three sites in the province of Thi-Qar

The objective of this investigation is to evaluate the level of the some minerals (sodium, potassium and calcium) in the soil, forage and Cattle plasma, the specimens taken from three districts (Nasriya, Shatra and Sookalshukh) in Thi-qar province. Results showed an increase in the concentration of sodium element in soils Nasiriya, potassium, calcium element in soils Sookalshukh region compared to other regions, while plants Sookalshukh region showed the highest concentration of sodium and calcium either the Nasiriya area showed the highest concentration of potassium compared to other regions. The results show that significant (p≤0.05) increase in the cattle plasma sodium concentration in Nasriya region compared with the Shatra and Sookalshukh , significant (p≤0.05) increase in Cattle plasma potassium concentration in Nasriya district compared with Shatra and Sookalshukh but there is significance (p≤0.05) change found in Cattle plasma calcium in shatra compared with the two studied areas. There was a highly significant between grass and animal sodium and potassium element, soil and grass and animals of the calcium element.

Hypokalemia during acute metabolic acidosis on hemodilution with succinylated gelatin in rats

BackgroundExtracellular metabolic acidosis of mineral origin is commonly associated with plasma hyperkalemia. Nevertheless, in previous experiments, animals subjected to acute metabolic acidosis induced by normovolemic hemodilution using a colloidal volume replacement solution containing succinylated gelatin (gelafundin), developed a hypokalemic state with concomitant marked increases in diuresis and renal potassium excretion. In the present study, the succinylated gelatin's impact on diuresis and consequently potassium excretion was studied. Material and methodsAnesthetized Wistar rats were subjected to acute metabolic acidosis either due to normovolemic hemodilution with gelafundin (group I) or HCl application (groups II and III). Animals of group III received mannitol in addition. Blood gas analyses were performed regularly. Urine was continuously collected, and the excreted volume as well as potassium concentration was measured. ResultsIn all groups, mean base excess value was about −3.0 mEq/L. Plasma potassium concentration decreased from 5.0 mM to 4.5 mM in group I, whereas it was almost constant in groups II and III. The urine volume amounted to 2300 μL in groups I and III and 1000 μL in group II. Excreted total amount of potassium in urine was 340 μmol (group I), 125 μmol (group II), and 230 μmol (group III), respectively. ConclusionsThe employed volume replacement solution leads to increased diuresis induced by excretion of succinylated gelatin, which also sufficiently accounts for enhanced potassium loss into urine and decreased plasma potassium concentration. Therefore, generalization of the connection between acute metabolic acidosis and plasma hyperkalemia, as often stated in literature, is not justified.

Factors Influencing the Relationship Between the Dose of Amlodipine Required for Blood Pressure Control and Change in Blood Pressure in Hypertensive Cats.

BackgroundHypertension is a common problem in elderly cats. In most cats, systolic blood pressure (SBP) of <160 mmHg is achieved in response to amlodipine besylate at either 0.625 or 1.25 mg q24h. The individual cat factors determining dose requirement dose have not been explored.AimsTo determine whether individual cat factors influence the dose of amlodipine required to achieve adequate blood pressure control and to determine whether factors other than the prescribed dose of drug alter the achieved plasma amlodipine concentrations.MethodsFifty‐nine hypertensive cats that required 0.625 mg (A) and 41 cats that required 1.25 mg (B) amlodipine to reach a target SBP of <160 mmHg were identified, and plasma amlodipine concentrations were determined. Comparisons were made between groups, and multivariable linear regression models were performed to investigate predictors of antihypertensive response.ResultsCats that required a greater dose of amlodipine had significantly higher SBP at diagnosis of hypertension (A: (median [25th, 75th percentile]) 182 [175,192] mmHg; B: 207 [194,217] mmHg, P < .001), but comparable blood pressure was achieved after treatment. Plasma amlodipine concentrations were directly related to the dose of amlodipine administered. At diagnosis, cats in group B had significantly lower plasma potassium concentration (A: 4.1 [3.8,4.5]; B: 3.8 [3.6,4.2] mEq/L, P < .01). Weight did not differ between groups. The decrease in SBP was directly and independently associated with the SBP at diagnosis and the plasma amlodipine concentration.Conclusions and Clinical ImportanceCats with higher blood pressure at diagnosis might require a greater dose of amlodipine to control their blood pressure adequately. Differences in amlodipine pharmacokinetics between cats do not seem to play a role in the antihypertensive response.

SY 03-3 OVERVIEW OF SOMATIC MUTATIONS AND EPIGENETIC REGULATION OF ALDOSTERONE PRODUCING ADENOMA (APA)

Log in or Register Subscribe to journalSubscribe Get new issue alertsGet alerts Submit your manuscript Enter your Email address: Wolters Kluwer Health may email you for journal alerts and information, but is committed to maintaining your privacy and will not share your personal information without your express consent. For more information, please refer to our Privacy Policy. Subscribe to eTOC Secondary Logo Journal Logo All Articles Images Videos Podcasts Blogs Advanced Search Toggle navigation Subscribe Register Login Articles & Issues Current IssuePrevious IssuesPublished Ahead-of-Print For Authors Submit a ManuscriptInformation for AuthorsLanguage Editing ServicesAuthor Permissions Journal Info About the JournalEditorial BoardAdvertisingOpen AccessSubscription ServicesReprintsRights and Permissions Latest ArticlesPodcastsTwitter All Articles Images Videos Podcasts Blogs Advanced Search

Caffeine Alters Blood Potassium and Catecholamine Concentrations but not the Perception of Pain and Fatigue with a 1 km Cycling Sprint

Background: Caffeine has been used by some athletes to improve short-term high-intensity exercise performance; however, the literature is equivocal. Objectives: The objective of this study was to investigate the effects of caffeine on plasma potassium and catecholamine concentrations, pain and fatigue perception, to determine whether potassium ion handling and altered perception related to the central nervous system are associated with enhanced performance during a 1 km cycling time trial. Methods: Thirteen well trained men with a mean age of 27 ± 6 yrs (body mass: 76.4 ± 6.4 kg, height: 180 ± 7 cm, and max: 57.5 ± 4.6 ml·kg -1 ·min -1 ) were recruited. Participants were randomized to a caffeine (5 mg·kg -1 ) or a placebo condition using a double blind, cross over design. Results: Caffeine had no significant effects on the 1 km time-trial performance indicators of time (82.1 ± 2.4 vs. 81.9 ± 3.9s), peak (633.0 ± 83.6 vs. 638.7 ± 110.1 watts) or average power (466.0 ± 37.3 vs. 467.5 ± 59.9 watts; caffeine and placebo conditions respectively). In addition, caffeine had no significant effect on oxygen consumption () (4.11 ± 0.24 vs 4.06 ± 0.29 L),the perception of pain (5.6 ± 2.4 vs. 5.5 ± 2.6) or fatigue (7.1 ± 1.8 vs.7.1 ± 1.8: caffeine and placebo conditions respectively). There was a significantly greater increase in post-exercise blood lactate (p<0.05) and catecholamines (p<0.05) as well as a lower pre-exercise blood potassium concentration (p<0.05) in the caffeine condition. Conclusions: The results suggest that caffeine can enhance certain metabolic parameters, but these changes were unable to augment short-distance (1km), high-intensity cycling performance. Keywords: ergogenic, anaerobic exercise, performance, oxygen consumption

Plasma Potassium Concentration on Admission Correlates with Neurologic Outcome in Traumatic Brain Injury Patients Treated with Targeted Temperature Management: A Post Hoc Analysis of a Multicenter Randomized Controlled Trial

Recent studies have focused on the association between plasma electrolytes, particularly potassium level and neurologic outcomes in patients with traumatic brain injury (TBI). We hypothesized that potassium level on admission is an indicator for initiation of targeted temperature management in patients with severe TBI. We re-evaluated the Brain Hypothermia Study data based on the potassium levels on admission (i.e.,hypokalemia [<3.5 mEq/L] or normokalemia [3.5-5 mEq/L]) and compared these values and Glasgow Outcome Scale scores at 6 months by per protocol analysis. Consequently, 135 patients were enrolled. Finally, groups 50 and 23 patients with hypokalemia and 34 and 23 patients with normokalemia were allocated to mild therapeutic hypothermia (MTH) and fever control groups, respectively. Baseline characteristics, complication rates, and favorable neurologic outcome rates were compared between the two groups. In the normokalemia patients, fever control management was associated with a significant increase in favorable neurologic outcome compared with those in the MTH group (68.2% vs. 35.3%; P= 0.03). The complication rate was significantly higher in the MTH group than in the fever control group for patients with normokalemia (23.4% vs. 0%; P= 0.03). Conversely, hypokalemia patients in the MTH group revealed relatively better favorable neurologic outcomes compared with those in the fever control group (52.0% vs. 39.1%; P= 0.33). The initial potassium level may be an indicator in determining appropriate targeted temperature management for patients with TBI. Fever control may be considered instead of MTH for normokalemia patients with TBI on admission.

Evaluation of 2 portable ion-selective electrode meters for determining whole blood, plasma, urine, milk, and abomasal fluid potassium concentrations in dairy cattle

Two low-cost ion-selective electrode (ISE) handheld meters (CARDY C-131, LAQUAtwin B-731; Horiba Ltd., Albany, NY) have recently become available for measuring the potassium concentration ([K+]) in biological fluids. The primary objective of this study was to characterize the analytical performance of the ISE meters in measuring [K+] in bovine whole blood, plasma, urine, milk, and abomasal fluid. We completed 6 method comparison studies using 369 whole blood and plasma samples from 106 healthy periparturient Holstein-Friesian cows, 138 plasma samples from 27 periparturient Holstein-Friesian cows, 92 milk samples and 204 urine samples from 16 lactating Holstein-Friesian cows, and 94 abomasal fluid samples from 6 male Holstein-Friesian calves. Deming regression and Bland-Altman plots were used to characterize meter performance against reference methods (indirect ISE, Hitachi 911 and 917; inductively coupled plasma-optical emission spectroscopy). The CARDY ISE meter applied directly in plasma measured [K+] as being 7.3% lower than the indirect ISE reference method, consistent with the recommended adjustment of +7.5% when indirect ISE methods are used to analyze plasma. The LAQUAtwin ISE meter run in direct mode measured fat-free milk [K+] as being 3.6% lower than the indirect ISE reference method, consistent with a herd milk protein percentage of 3.4%. The LAQUAtwin ISE meter accurately measured abomasal fluid [K+] compared to the indirect ISE reference method. The LAQUAtwin ISE meter accurately measured urine [K+] compared to the indirect ISE reference method, but the median measured value for urine [K+] was 83% of the true value measured by inductively coupled plasma-optical emission spectroscopy. We conclude that the CARDY and LAQUAtwin ISE meters are practical, low-cost, rapid, accurate point-of-care instruments suitable for measuring [K+] in whole blood, plasma, milk, and abomasal fluid samples from cattle. Ion-selective electrode methodology is not suitable for measuring [K+] in bovine urine.

In Primary Aldosteronism, Mineralocorticoids Influence Exosomal Sodium-Chloride Cotransporter Abundance.

Distal tubular sodium retention is a potent driver of hypertension, and the thiazide-sensitive sodium-chloride cotransporter (NCC) has a key role in this process. In humans, factors regulating NCC are unclear, but in animal models, aldosterone is a potent regulator, possibly via effects on plasma potassium. We studied the effects of the mineralocorticoid fludrocortisone on the abundance of NCC and its phosphorylated form (pNCC) as well as WNK lysine deficient protein kinase 4 (WNK4) and STE20/SPS1-related, proline alanine-rich kinase (SPAK) in human urinary exosomes. We isolated exosomes from daily urine samples in 25 patients undergoing fludrocortisone suppression testing (100 μg every 6 hours for 4 days) to diagnose or exclude primary aldosteronism. Over the course of the test, NCC levels increased 3.68-fold (P<0.01) and pNCC levels increased 2.73-fold (P<0.01) relative to baseline. The ratio of pNCC/NCC dropped by 48% (P<0.01). The abundance of WNK4 increased 3.23-fold (P<0.01), but SPAK abundance did not change significantly (P=0.14). Plasma potassium concentration strongly and negatively correlated with pNCC, NCC, and WNK4 abundance (P<0.001 for all). This study shows that, in humans, mineralocorticoid administration is associated with a rapid increase in abundance of NCC and pNCC, possibly via the WNK pathway. These effects may be driven by changes in plasma potassium.

A Pilot Study Exploring the Plasma Potassium Variation in Dogs Undergoing Steroid Therapy and Its Clinical Importance

In most situations in veterinary medicine, glucocorticoids are the drugs of choice used, that is, to reduce the inflammatory response or limit an inappropriate immune response. Their use in long-term therapy may cause side effects that may weaken the patient. The aim of the study was to evaluate possible variations in the plasma potassium concentrations and their clinical relevance in dogs undergoing steroid therapy with methylprednisolone in anti-inflammatory doses. The study used a sample of 21 dogs (n = 21) presented for consultation, with a clinical condition requiring a corticosteroid therapeutic protocol with an anti-inflammatory dose of methylprednisolone. All the individuals were submitted to a corticosteroid therapeutic protocol administered orally during 18 days. During this period, 3 time points were considered: T0 (the day the prescription was first given), T1 (3 days later), and T2 (8 days later). Blood samples were collected from a peripheral vein to measure plasma potassium concentrations in T0, T1, and T2. Corticosteroid therapy on an outpatient basis statistically significantly decreased plasma potassium levels, especially between T1 and T2 (P = .03). The plasma potassium levels decreased in 12.5% of the males, compared with a decrease of 23.1% in the females. No statistically significant relationships were observe between the decreased plasma potassium levels and age, clinical condition, and patient׳s body weight. However, we found a statistically significant association between decreased plasma potassium levels and sex. The study results may justify the need for the systematic prescription of potassium supplements in patients undergoing steroid therapy, similar to what already occurs in human medicine.

Concentration of Potassium in Plasma, Erythrocytes, and Muscle Tissue in Cows with Decreased Feed Intake and Gastrointestinal Ileus.

BackgroundHealthy cows consume large amounts of potassium and a sudden loss in appetite can lead to hypokalemia. The routine method to evaluate potassium homeostasis is the measurement of the extracellular potassium in plasma or serum, but this does not provide information about the intracellular potassium pool.Hypothesis/ObjectivesTo evaluate potassium homeostasis by comparing the extracellular and intracellular potassium concentration in cows with reduced feed intake and gastrointestinal ileus.AnimalsTwenty cows 1–3 days postpartum (group 1) and 20 cows with gastrointestinal ileus (group 2).MethodsObservational cross‐sectional study. Plasma potassium was measured by using an ion‐sensitive electrode. Intracellular potassium was measured in erythrocytes and muscle tissue (muscle biopsy) by using inductively coupled plasma optical emission spectroscopy.ResultsCows of group 1 did not have hypokalemia. Overall cows with gastrointestinal ileus were hypokalemic (mean ± SD, 2.9 mmol/L ± 0.78), but potassium concentration in erythrocytes and muscle tissue was not lower than in postpartum cows. Intracellular potassium in erythrocytes varied very widely; group 1: 3497–10735 mg/kg (5559 ± 2002 mg/kg), group 2: 4139–21678 mg/kg (7473 ± 4034 mg/kg). Potassium in muscle tissue did not differ between group 1 (3356 ± 735 mg/kg wet weight) and group 2 (3407 ± 1069 mg/kg wet weight). No association between extracellular and intracellular potassium concentrations was detected.Conclusions and clinical importanceThat measurement of plasma potassium concentration is not sufficient to evaluate potassium metabolism of cows.

Comparative dose response using the intravenous versus enteral route of administration for potassium replenishment

To compare the change in potassium concentration (dose-response) using the intravenous versus enteral route for potassium replenishment. Cross-sectional analysis of individual potassium chloride doses with resulting changes in plasma potassium concentrations in intensive care patients. Potassium chloride was administered according to potassium replenishment protocols. For inclusion, doses were required to have pre- and post-dose plasma potassium concentrations obtained within 8hours of administration. Medical and surgical intensive care units of a United States Veterans Affairs Medical Center. The primary outcome was the dose-response slope for intravenous versus enteral potassium administration as estimated by linear regression analysis. Multivariable linear regression was employed to adjust for potential confounders. The sample had 278 potassium chloride doses administered to 142 patients. The potassium concentration change per 20mmol of potassium chloride was similar for intravenous and enteral routes, 0.25mmol/L (95% confidence interval 0.16-0.33) versus 0.27mmol/L (0.15-0.39) respectively (p=0.73). Multivariable linear regression did not alter results. The success of achieving a minimum potassium concentration defined by the specific protocol was similar for intravenous (61%) and enteral (59%) administration. Overall, 77% of potassium chloride doses were administered at a time when patients were eligible to receive an enteral dosage form. The enteral route was as effective as the intravenous route in increasing the plasma potassium concentration. The enteral route was widely available for potassium replenishment. Despite enteral route availability and the well-known reliability of potassium chloride absorption, the majority of doses were administered intravenously.

Moving from Measuring to Predicting Bycatch Mortality: Predicting the Capture Condition of a Longline-Caught Pelagic Shark

Incidental fisheries capture has been identified as having a major effect on shark populations throughout the world. However, factors that contribute to the mortality of shark bycatch during fisheries capture are not fully understood. Here, we investigated the effects of capture duration, sea surface temperature, and shark total length (snout to the tip of the upper caudal lobe) on the physiology and condition of longline-caught bronze whalers, Carcharhinus brachyurus. Plasma lactate and potassium concentration had a positive linear relationship with capture duration, indicating that this species experiences increasing physiological challenges while on fishing gear. Additionally, we used stereotype logistic regression models to determine variables that could predict the capture condition of sharks (categorized as “healthy”, “sluggish”, or “moribund or dead”). In these models, elevated plasma lactate concentration, plasma potassium concentration, and capture duration increased the likelihood of C. brachyurus being captured in a “sluggish” condition or in a “moribund or dead” condition. After plasma lactate concentration exceeded 27.4 mmol/L, plasma potassium concentration exceeded 8.3 mmol/L, or capture durations exceeded 293 minutes, the majority of captured sharks (>50%) were predicted to be “moribund or dead.” We recommend that a reduction in the amount of time longlines are left fishing (soak time) will reduce immediate and post-release mortality in C. brachyurus bycatch and that our methods could be applied to identify causes of fisheries-induced mortality in future studies. The identification of operational, environmental, and biological variables contributing to poor condition will be necessary to implement conservation strategies that reduce mortality during capture.