| Autor: |
Qayyum, MS, Freemantle, CA, Carey, CJ, Page, BC, Soper, N, Paterson, DJ, Robbins, PA |
| Zdroj: |
Experimental Physiology; September 1993, Vol. 78 Issue: 5 p639-648, 10p |
| Abstrakt: |
Muscle potassium (K+) content decreases during exercise. Previous studies, in humans, have used measurements of arteriovenous plasma potassium concentration differences (AV delta[K+]) and/or muscle biopsy to measure the loss of muscle K+ during exercise. In the current study a non‐invasive method was developed to measure skeletal muscle K+ before and after exercise, using an isotope of K+, potassium‐43 (43K+). Twelve subjects performed single‐leg extension exercise for 2 h at 50% of their maximum predicted heart rate. The level of radioactivity from the quadriceps femoris was determined before exercise and during two periods post‐exercise. After correction for counts arising outside the exercised muscle, we estimate a decrease in muscle K+ content of 3.2 +/− 1.55% (mean +/− S.E.M.) following exercise. The muscle K+ was not restored following 75 min of recovery. The decrease in muscle K+ following exercise in our study is considerably less than that suggested by previous studies using AV delta[K+] measurements but not so dissimilar from results obtained using muscle biopsy. We conclude that a small but significant loss of K+ occurs following prolonged dynamic exercise, and that complete recovery of muscle K+ is slow. |
| Databáze: |
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