Microdialysis and the measurement of muscle interstitial K+ during rest and exercise in humans.
The purpose of this study was to examine whether microdialysis and the internal reference thallium-201 ((201)Tl) could accurately measure muscle interstitial K+ (Ki+) before, during, and after exercise. The relative loss of (201)Tl and simultaneous relative recovery of K+ were measured in vitro for 12 microdialysis probes that were bathed in Ringer acetate medium and perfused at various flows (3-10 microl/min). (201)Tl loss was linearly related to K+ recovery, and their level of agreement was not different from zero. Microdialysis and (201)Tl were then used to measure Ki+ in the gastrocnemius medialis muscle of four humans during rest and static plantar flexion exercise. At rest, Ki+ was 3.9-4.3 mmol/l when the perfusate flow was 2 or 5 microl/min. During exercise, Ki+ increased from 6.9 +/- 0.4 to 7.5 +/- 0.3 mmol/l at low to high intensity and declined to 5.2 +/- 0.3 mmol/l after exercise. These results suggest that large changes in Ki+ in human skeletal muscle can be accurately measured by using microdialysis and (201)Tl.
Green
S
S
Copenhagen Muscle Research Centre, Rigshospitalet, DK-2200 Copenhagen, Denmark. s.green@qut.edu.au
Bülow
J
J
Saltin
B
B
D000328:Adult; D005069:Evaluation Studies as Topic; D015444:Exercise / Q000502:physiology*; D005110:Extracellular Space / Q000378:metabolism; D005260:Female; D006801:Humans; D066298:In Vitro Techniques; D008297:Male; D017551:Microdialysis / Q000379:methods*; D018482:Muscle, Skeletal / Q000737:chemistry / Q000000981:diagnostic imaging / Q000378:metabolism*; D010477:Perfusion; D011188:Potassium / Q000032:analysis / Q000378:metabolism*; D011877:Radionuclide Imaging; D012146:Rest; D013794:Thallium Radioisotopes
D013794:Thallium Radioisotopes; D011188:Potassium