Impaired exercise performance and muscle Na+,K+-pump activity in renal transplantation and haemodialysis patients

• Published in: Nephrology, dialysis, transplantation Vol. 27; no. 5; pp. 2036 - 2043
• Main Authors: PETERSEN, Aaron C, LEIKIS, Murray J, MCMAHON, Lawrence P, KENT, Annette B, MURPHY, Kate T, XIAOFEI GONG, MCKENNA, Michael J
• Format: Journal Article
• Language: English
• Published: Oxford Oxford University Press 01.05.2012
• Subjects: Adult; Anesthesia. Intensive care medicine. Transfusions. Cell therapy and gene therapy; Biological and medical sciences; Case-Control Studies; Chronic Disease; Emergency and intensive care: renal failure. Dialysis management; Exercise - physiology; Female; Humans; Intensive care medicine; Isoenzymes - physiology; Kidney Diseases - physiopathology; Kidney Diseases - therapy; Kidney Transplantation; Male; Medical sciences; Middle Aged; Muscle Fatigue - physiology; Muscle, Skeletal - physiopathology; Oxygen Consumption - physiology; Potassium - blood; Renal Dialysis; Sodium-Potassium-Exchanging ATPase - physiology; Surgery (general aspects). Transplantations, organ and tissue grafts. Graft diseases; Surgery of the urinary system; Kidney disease; Physical exercise; Human; Urinary system disease; Hemodialysis; Fatigue; Inorganic element; muscle mass; Extrarenal dialysis; extrarenal potassium regulation; Renal failure; VO; Potassium; Strength
• ISSN: 0931-0509; 1460-2385
• DOI: 10.1093/ndt/gfr586

We examined whether abnormal skeletal muscle Na(+),K(+)-pumps underlie impaired exercise performance in haemodialysis patients (HDP) and whether these are improved in renal transplant recipients (RTx). Peak oxygen consumption ( O(2peak)) and plasma [K(+)] were measured during incremental exercise in 9RTx, 10 HDP and 10 healthy controls (CON). Quadriceps peak torque (PT), fatigability (decline in strength during thirty contractions), thigh muscle cross-sectional area (TMCSA) and vastus lateralis Na(+),K(+)-pump maximal activity, content and isoform (α(1)-α(3), β(1)-β(3)) abundance were measured. O(2peak) was 32 and 35% lower in RTx and HDP than CON, respectively (P < 0.05). PT was less in RTx and HDP than CON (P < 0.05) but did not differ when expressed relative to TMCSA. Fatigability was ∼1.6-fold higher in RTx (24 ± 11%) and HDP (25 ± 4%) than CON (15 ± 5%, P < 0.05). Na(+),K(+)-pump activity was 28 and 31% lower in RTx and HDP, respectively than CON (P < 0.02), whereas content and isoform abundance did not differ. Pooled (n = 28) O(2peak) correlated with Na(+),K(+)-pump activity (r = 0.45, P = 0.02). O(2peak) and muscle Na(+),K(+)-pump activity were depressed and muscle fatigability increased in HDP, with no difference observed in RTx. These findings are consistent with the possibility that impaired exercise performance in HDP and RTx may be partially due to depressed muscle Na(+),K(+)-pump activity and relative TMCSA.