title: Exercise, potassium, and muscle deconditioning post-thoracic organ transplantation.
abstract: Although muscle deconditioning appears to significantly limit peak exercise performance post-thoracic organ transplantation, few confirmatory data exist. Potassium (K+) regulation during exercise may reflect muscle deconditioning, since both peak plasma K+ concentration ([K+]) and the increase in plasma [K+] relative to energy expenditure (delta [K+]/W) are reduced in healthy individuals after training. This study compares delta [K+]/W during graded exercise and the change in [K+] (delta [K+]) during both exercise and recovery in 12 heart transplant (HT) recipients, 14 lung transplant (LT) recipients, and 7 healthy subjects. Plasma [K+] was determined from arterial blood sampled at rest; during the final 15 s of each power output; and at 1, 2, and 5 min postexercise. Peak oxygen consumption was significantly lower (P < 0.0001), whereas delta [K+]/W was significantly higher (P < 0.002) among the HT and LT groups. When delta [K+] during recovery was expressed relative to delta [K+] detected during activity, no difference at 1, 2, or 5 min postexercise was detected, although the absolute fall in plasma [K+] was greater among the healthy subjects in the 1st min (P < 0.0001). The rate of delta [K+] during recovery appears to reflect the rise seen during activity in all groups. These results suggest that [K+] regulation is altered during exercise in both HT and LT recipients and may reflect muscle deconditioning.
authors.affiliation: Department of Respiratory Medicine, Monash University, Alfred Hospital, Melbourne, Australia.
authors.forename: M J
authors.initials: MJ
authors.lastname: Hall
authors.forename: G I
authors.initials: GI
authors.lastname: Snell
authors.forename: E A
authors.initials: EA
authors.lastname: Side
authors.forename: D S
authors.initials: DS
authors.lastname: Esmore
authors.forename: E H
authors.initials: EH
authors.lastname: Walters
authors.forename: T J
authors.initials: TJ
authors.lastname: Williams
mesh_terms: D000328:Adult; D004734:Energy Metabolism; D005260:Female; D016027:Heart Transplantation; D006801:Humans; D016040:Lung Transplantation; D008297:Male; D009132:Muscles / Q000502:physiology*; D009994:Osmolar Concentration; D005082:Physical Exertion; D011184:Postoperative Period; D011188:Potassium / Q000097:blood*; D012016:Reference Values; D012119:Respiration
chemical_list: D011188:Potassium