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McKenna MJ, Renaud JM, Ørtenblad N, Overgaard K. A century of exercise physiology: effects of muscle contraction and exercise on skeletal muscle Na +,K +-ATPase, Na + and K + ions, and on plasma K + concentration-historical developments. Eur J Appl Physiol 2024; 124:681-751. [PMID: 38206444 PMCID: PMC10879387 DOI: 10.1007/s00421-023-05335-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2023] [Accepted: 09/27/2023] [Indexed: 01/12/2024]
Abstract
This historical review traces key discoveries regarding K+ and Na+ ions in skeletal muscle at rest and with exercise, including contents and concentrations, Na+,K+-ATPase (NKA) and exercise effects on plasma [K+] in humans. Following initial measures in 1896 of muscle contents in various species, including humans, electrical stimulation of animal muscle showed K+ loss and gains in Na+, Cl- and H20, then subsequently bidirectional muscle K+ and Na+ fluxes. After NKA discovery in 1957, methods were developed to quantify muscle NKA activity via rates of ATP hydrolysis, Na+/K+ radioisotope fluxes, [3H]-ouabain binding and phosphatase activity. Since then, it became clear that NKA plays a central role in Na+/K+ homeostasis and that NKA content and activity are regulated by muscle contractions and numerous hormones. During intense exercise in humans, muscle intracellular [K+] falls by 21 mM (range - 13 to - 39 mM), interstitial [K+] increases to 12-13 mM, and plasma [K+] rises to 6-8 mM, whilst post-exercise plasma [K+] falls rapidly, reflecting increased muscle NKA activity. Contractions were shown to increase NKA activity in proportion to activation frequency in animal intact muscle preparations. In human muscle, [3H]-ouabain-binding content fully quantifies NKA content, whilst the method mainly detects α2 isoforms in rats. Acute or chronic exercise affects human muscle K+, NKA content, activity, isoforms and phospholemman (FXYD1). Numerous hormones, pharmacological and dietary interventions, altered acid-base or redox states, exercise training and physical inactivity modulate plasma [K+] during exercise. Finally, historical research approaches largely excluded female participants and typically used very small sample sizes.
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Affiliation(s)
- Michael J McKenna
- Institute for Health and Sport, Victoria University, Melbourne, VIC, 8001, Australia.
- College of Physical Education, Southwest University, Chongqing, China.
- College of Sport Science, Zhuhai College of Science and Technology, Zhuhai, China.
| | - Jean-Marc Renaud
- Department of Cellular and Molecular Medicine, Neuromuscular Research Center, University of Ottawa, Ottawa, ON, Canada
| | - Niels Ørtenblad
- Department of Sports Science and Clinical Biomechanics, University of Southern Denmark, Odense, Denmark
| | - Kristian Overgaard
- Exercise Biology, Department of Public Health, Aarhus University, Aarhus, Denmark
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Sostaric S, Petersen AC, Goodman CA, Gong X, Aw TJ, Brown MJ, Garnham A, Steward CH, Murphy KT, Carey KA, Leppik J, Fraser SF, Cameron-Smith D, Krum H, Snow RJ, McKenna MJ. Oral digoxin effects on exercise performance, K + regulation and skeletal muscle Na + ,K + -ATPase in healthy humans. J Physiol 2022; 600:3749-3774. [PMID: 35837833 PMCID: PMC9541254 DOI: 10.1113/jp283017] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2022] [Accepted: 07/08/2022] [Indexed: 11/30/2022] Open
Abstract
Abstract We investigated whether digoxin lowered muscle Na+,K+‐ATPase (NKA), impaired muscle performance and exacerbated exercise K+ disturbances. Ten healthy adults ingested digoxin (0.25 mg; DIG) or placebo (CON) for 14 days and performed quadriceps strength and fatiguability, finger flexion (FF, 105%peak‐workrate, 3 × 1 min, fourth bout to fatigue) and leg cycling (LC, 10 min at 33% VO2peak and 67% VO2peak, 90% VO2peak to fatigue) trials using a double‐blind, crossover, randomised, counter‐balanced design. Arterial (a) and antecubital venous (v) blood was sampled (FF, LC) and muscle biopsied (LC, rest, 67% VO2peak, fatigue, 3 h after exercise). In DIG, in resting muscle, [3H]‐ouabain binding site content (OB‐Fab) was unchanged; however, bound‐digoxin removal with Digibind revealed total ouabain binding (OB+Fab) increased (8.2%, P = 0.047), indicating 7.6% NKA–digoxin occupancy. Quadriceps muscle strength declined in DIG (−4.3%, P = 0.010) but fatiguability was unchanged. During LC, in DIG (main effects), time to fatigue and [K+]a were unchanged, whilst [K+]v was lower (P = 0.042) and [K+]a‐v greater (P = 0.004) than in CON; with exercise (main effects), muscle OB‐Fab was increased at 67% VO2peak (per wet‐weight, P = 0.005; per protein P = 0.001) and at fatigue (per protein, P = 0.003), whilst [K+]a, [K+]v and [K+]a‐v were each increased at fatigue (P = 0.001). During FF, in DIG (main effects), time to fatigue, [K+]a, [K+]v and [K+]a‐v were unchanged; with exercise (main effects), plasma [K+]a, [K+]v, [K+]a‐v and muscle K+ efflux were all increased at fatigue (P = 0.001). Thus, muscle strength declined, but functional muscle NKA content was preserved during DIG, despite elevated plasma digoxin and muscle NKA–digoxin occupancy, with K+ disturbances and fatiguability unchanged.
![]() Key points The Na+,K+‐ATPase (NKA) is vital in regulating skeletal muscle extracellular potassium concentration ([K+]), excitability and plasma [K+] and thereby also in modulating fatigue during intense contractions.
NKA is inhibited by digoxin, which in cardiac patients lowers muscle functional NKA content ([3H]‐ouabain binding) and exacerbates K+ disturbances during exercise. In healthy adults, we found that digoxin at clinical levels surprisingly did not reduce functional muscle NKA content, whilst digoxin removal by Digibind antibody revealed an ∼8% increased muscle total NKA content. Accordingly, digoxin did not exacerbate arterial plasma [K+] disturbances or worsen fatigue during intense exercise, although quadriceps muscle strength was reduced. Thus, digoxin treatment in healthy participants elevated serum digoxin, but muscle functional NKA content was preserved, whilst K+ disturbances and fatigue with intense exercise were unchanged. This resilience to digoxin NKA inhibition is consistent with the importance of NKA in preserving K+ regulation and muscle function.
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Affiliation(s)
- Simon Sostaric
- Institute for Health and Sport, Victoria University, Melbourne, Australia
| | - Aaron C Petersen
- Institute for Health and Sport, Victoria University, Melbourne, Australia
| | - Craig A Goodman
- Institute for Health and Sport, Victoria University, Melbourne, Australia.,Centre for Muscle Research, Department of Anatomy and Physiology, University of Melbourne, Parkville, Australia
| | - Xiaofei Gong
- Institute for Health and Sport, Victoria University, Melbourne, Australia
| | - Tai-Juan Aw
- Department of Epidemiology and Preventive Medicine, Monash University, Alfred Hospital, Melbourne, Australia
| | - Malcolm J Brown
- Department of Biochemistry and Pharmacology, University of Melbourne, Melbourne, Australia
| | - Andrew Garnham
- Institute for Health and Sport, Victoria University, Melbourne, Australia
| | - Collene H Steward
- Institute for Health and Sport, Victoria University, Melbourne, Australia
| | - Kate T Murphy
- Institute for Health and Sport, Victoria University, Melbourne, Australia.,Centre for Muscle Research, Department of Anatomy and Physiology, University of Melbourne, Parkville, Australia
| | - Kate A Carey
- School of Women's and Children's Health, University of New South Wales, Sydney, Australia
| | - James Leppik
- Institute for Health and Sport, Victoria University, Melbourne, Australia
| | - Steve F Fraser
- Institute of Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University, Melbourne, Australia
| | - David Cameron-Smith
- Singapore Institute for Clinical Sciences, Agency for Science, Technology and Research, Singapore
| | - Henry Krum
- Department of Epidemiology and Preventive Medicine, Monash University, Alfred Hospital, Melbourne, Australia
| | - Rodney J Snow
- Institute of Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University, Melbourne, Australia
| | - Michael J McKenna
- Institute for Health and Sport, Victoria University, Melbourne, Australia
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Shah P, Pellicori P, Hanning I, Zhang J, Clark AL, Bhandari S. The effect of digoxin on renal function in patients with heart failure. BMC Nephrol 2021; 22:349. [PMID: 34702219 PMCID: PMC8549227 DOI: 10.1186/s12882-021-02562-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2021] [Accepted: 05/17/2021] [Indexed: 12/03/2022] Open
Abstract
Introduction Digoxin is used in patients with chronic heart failure (CHF) who remain symptomatic despite optimal medical treatment. Impaired renal function is commonly associated with CHF. We investigated the relation between digoxin use and change in renal function over time in patients with CHF. Methods One thousand two hundred forty-one patients with symptoms and signs of CHF (average age 72 years (64% male), and median NTproBNP 1426 ng/l (interquartile range 632–2897) were divided into four groups: never on digoxin (N = 394); digoxin throughout (N = 449); started digoxin at some point after baseline (N = 367); and stopped digoxin at some point after baseline (N = 31). The rate of change of estimated glomerular filtration rate (eGFR) was calculated using linear regression. Results Patients on digoxin throughout had a significantly greater rate of decline in eGFR per year than patients not on digoxin throughout (mean (± standard deviation); − 5 (14) ml/min/1.73m2 per year v − 2 (11) ml/min/1.73m2 per year, P = 0.02). In those patients who started digoxin during follow up, there was no significant difference in the rate of decline in eGFR before and after starting digoxin. There was no correlation between baseline eGFR (or rate of decline in eGFR) and age, haemoglobin or NTproBNP. Compared to patients taking both angiotensin-converting-enzyme inhibitor (ACEi) or angiotensin receptor blockers (ARB) and beta-blocker (BB), patients who were not taking an ACEi/ARB or BB had a numerically faster rate of decline in eGFR, although this was not statistically significant. Conclusion The rate of decline in renal function is greater in patients with CHF who are taking digoxin.
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Affiliation(s)
- Parin Shah
- Department of Cardiology, Hull York Medical School, Hull and East Yorkshire Medical Research and Teaching Centre, Castle Hill Hospital, Cottingham, Kingston upon Hull, HU16 5JQ, UK.
| | - Pierpaolo Pellicori
- Department of Cardiology, Hull York Medical School, Hull and East Yorkshire Medical Research and Teaching Centre, Castle Hill Hospital, Cottingham, Kingston upon Hull, HU16 5JQ, UK
| | - Ian Hanning
- Biochemistry, Pathology department, Hull & East Yorkshire Hospitals NHS Trust, Hull, UK
| | - Jufen Zhang
- Clinical Trials Unit, Postgraduate Medical Institute, Faculty of Medical Science, Anglia Ruskin University, Bishop Hall Lane, Chelmsford, Essex, CM1 1SQ, UK
| | - Andrew L Clark
- Department of Cardiology, Hull York Medical School, Hull and East Yorkshire Medical Research and Teaching Centre, Castle Hill Hospital, Cottingham, Kingston upon Hull, HU16 5JQ, UK
| | - Sunil Bhandari
- Department of Renal Medicine, Hull and East Yorkshire Hospitals NHS Trust and Hull York Medical School, Heslington, UK
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de Denus S, Tardif JC, White M, Bourassa MG, Racine N, Levesque S, Ducharme A. Quantification of the risk and predictors of hyperkalemia in patients with left ventricular dysfunction: a retrospective analysis of the Studies of Left Ventricular Dysfunction (SOLVD) trials. Am Heart J 2006; 152:705-12. [PMID: 16996842 DOI: 10.1016/j.ahj.2006.05.030] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/12/2004] [Accepted: 05/02/2006] [Indexed: 01/11/2023]
Abstract
BACKGROUND Limited data are available to predict the occurrence of hyperkalemia. Risk assessment is complicated by the lack of consistency of definition between trials. METHODS We conducted a retrospective analysis of the SOLVD to evaluate the incidence of hyperkalemia and the value of several baseline characteristics as predictors of hyperkalemia in patients with left ventricular dysfunction. RESULTS The incidence of hyperkalemia was 6.0% and 1.1% using a definition of > or = 5.5 and > or = 6.0 mmol/L, respectively. Independent predictors of hyperkalemia (> or = 5.5 mmol/L) were randomization to enalapril, baseline serum creatinine, serum potassium, New York Heart Association functional class III or IV, a history of diabetes, and atrial fibrillation (all P < .05). The use of loop diuretics was also associated with an increased risk of hyperkalemia but only in patients included in the SOLVD prevention trial. Similar results were obtained when renal function was evaluated using the estimated creatinine clearance. CONCLUSIONS The definition of hyperkalemia is important when evaluating its incidence in clinical trials. Renal dysfunction, baseline serum potassium, diabetes, atrial fibrillation, New York Heart Association functional class, and treatment with an angiotensin-converting enzyme inhibitor are factors associated with the development of hyperkalemia in patients with left ventricular dysfunction. More specifically, our results suggests that before initiating drugs that can cause hyperkalemia in patients with heart failure, a strong consideration should be given to calculate creatinine clearance and that patients with a creatinine clearance < 60 mL/min should undergo a close monitoring of their serum potassium to prevent the development of hyperkalemia.
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Affiliation(s)
- Simon de Denus
- Faculty of Pharmacy, University of Montreal, Montreal, Quebec, Canada
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