Abstract des Autors

The purpose of this study was to examine whether microdialysis and the internal reference thallium-201 (201Tl) could accurately measure muscle interstitial K+ (K+i) before, during, and after exercise. The relative loss of 201TI, 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 micro-l/min). 201TI loss was linearly related to K+ recovery, and their level of agreement was not different from zero. Microdialysis and 201TI were then used to measure K+i in the gastrocnemius medialis muscle of four humans during rest and static plantar flexion exercise. At rest, K+i was 3.9-4.3 mmol/l when the perfusate flow was 2 or 5 micro-l/min. During exercise, K+i 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 K+i in human skeletal muscle can be accurately measured by using microdialysis and 201TI. Verf.-Referat