Extracellular K+ concentration and K+ Balance of the gastrocnemius muscle of the dog during exercise

Hirche, Hans-Jürgen; Schumacher, Erhard; Hagemann, H. H.

doi:10.1007/bf00580975

Cited by 79 publications

(36 citation statements)

References 20 publications

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“…This very rapid fall has been observed by others (Hirche et al 1980;Fedde et al 1989;Juel et al 1989), but has also in previous years escaped attention, leading to erroneous conclusions about the effects of exercise on plasma potassium (Felig, Johnson, Levitt, Cunningham, Keefe & Boglioli, 1982).…”

Section: Causes Of Rise In Plasma Potassium Concentrationmentioning

confidence: 75%

“…Previous investigations, some of which date from the 1930s, conclude that potassium release from active muscle cells is caused by local electric events (Fenn, 1938;Hnik et al 1976;Hazeyama & Sparks, 1979). Isolated muscles release potassium during stimulation (Hirche et al 1980), and when smaller muscle groups with intact perfusion are activated in vivo, a negative arterio-venous difference can be clearly demonstrated (Sj0gaard, 1986;Juel et al 1989). Also, the intact non-ischaemic heart transiently releases potassium during increments in heart rate, although the amount is too small to affect the plasma concentration of mixed venous blood (Ilebekk, Andersen & Sejersted, 1986).…”

Section: Causes Of Rise In Plasma Potassium Concentrationmentioning

confidence: 99%

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Plasma potassium changes with high intensity exercise.

Medbø

Sejersted

1990

The Journal of Physiology

237

153

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SUMMARY1. Exercise seems to change the extracellular potassium concentration far beyond the narrow limits seen in resting subjects. To examine alterations in plasma potassium concentration during exercise, twenty healthy, well-trained men ran on the treadmill at 6 deg inclination with catheters inserted in the femoral vein and artery.2. During 1 min exhausting exercise plasma potassium concentration rose in parallel in the vein and artery, reaching peak post-exercise values of 8-34 + 023 mmol 1-and 817 +0-29 mmol 1-1. After 3 min recovery the potassium concentration was 0'50 + 0 05 mmol 1-1 below pre-exercise values. Both the rise of plasma potassium concentration during exercise and the decline during recovery followed exponential time courses with a half-time of 25 s.3. Exercise at reduced intensity showed that the peak post-exercise potassium concentration was linearly related to the exercise intensity. Individual resting, peak and nadir values were proportionally related.4. The increased potassium concentration during exercise can be explained in full by the electrical activity in the exercising muscles. Repeated 1 min exhausting exercise bouts revealed no relationship between potassium concentration and plasma pH nor glycogen break-down.5. All of the observations fit a simple model of potassium efflux from active muscle and elimination from blood with the following characteristics: the efflux increases (decreases) stepwise at the onset (end) of exercise, and the efflux rate during exercise increases with exercise intensity. Potassium is eliminated from blood by a proportional regulator which may be the Na+-K+ pump of the exercising muscle. Extracellular potassium is indirectly linked to the pump stimulus, and the rate of reuptake is proportional to the extracellular accumulation. Thus no limited maximal power for potassium uptake was found. The post-exercise undershoot of 0'5 mmol 1-1 can be explained by a higher gain of the pump after exercise.6. The large, rapid changes in the plasma potassium concentration during and after exercise is due to the first order kinetics of the reuptake mechanism rather than to a limited power to take up potassium.* To whom correspondence and reprint requests should be sent, to PO Box 8149 Dep., at the address above. MS 7602 J. I. MEDB0 AND 0. M. SEJERSTED

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Section: Causes Of Rise In Plasma Potassium Concentrationmentioning

confidence: 75%

Section: Causes Of Rise In Plasma Potassium Concentrationmentioning

confidence: 99%

Plasma potassium changes with high intensity exercise.

Medbø

Sejersted

1990

The Journal of Physiology

237

153

View full text Add to dashboard Cite

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“…In fact, during contraction K ϩ is continuously released from the muscle (14,32). The nature of the K ϩ loss from the muscle during exercise has been attributed to an incomplete reuptake of K ϩ with each depolarization (33). Thus, muscle fatigue may then be related to changes in K ϩ gradient and water concentration across the sarcolemma membrane and not only to energy metabolism.…”

Section: Discussionmentioning

confidence: 99%

Expression of aquaporin-4 in fast-twitch fibers of mammalian skeletal muscle.

Frigeri¹,

Nicchia²,

Verbavatz³

et al. 1998

J. Clin. Invest.

176

158

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In this study we analyzed the expression of aquaporin-4 (AQP4) in mammalian skeletal muscle. Immunohistochemical experiments revealed that affinity-purified AQP4 antibodies stained selectively the sarcolemma of fast-twitch fibers. By immunogold electron microscopy, little or no intracellular labeling was detected. Western blot analysis showed the presence of two immunopositive bands with apparent molecular masses of 30 and 32 kD specifically present in membrane fraction of a fast-twitch rat skeletal muscle (extensor digitorum longus, EDL) and not revealed in a slow-twitch muscle (soleus). PCR Southern blot experiments resulted in a selective amplification in EDL of a 960-bp cDNA fragment encoding for the full-length rat form of AQP4. Functional experiments carried out on isolated skeletal muscle bundle fibers demonstrated that the osmotic response is faster in EDL than in soleus fibers isolated from the same rat. These results provide for the first time evidence for the expression of an aquaporin in skeletal muscle correlated to a specific fiber-type metabolism.

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“…There is a net and large K + efflux in exercising skeletal muscle resulting in a decrease in the intracellular K + (K +) concentration and an increase in the extracellular K + (Ko) concentration (Hnik et al, 1976(Hnik et al, , 1986Hirche et al, 1980;Juel, 1986;Medbo & Sejersted, 1990). The various effects of an increased Ko concentration on the sarcolemma are well known.…”

confidence: 99%

The effect of K+ on the recovery of the twitch and tetanic force following fatigue in the sartorius muscle of the frog, Rana pipiens

Renaud

Comtois

1994

J Muscle Res Cell Motil

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The goal of this study was to investigate how an increase in the extracellular K+ (K0+) concentration immediately after fatigue affects the recovery of the resting potential, the twitch and tetanic contraction of frog sartorius muscle to further understand the role of K+ in the mechanism of fatigue. Resting potentials were measured with conventional microelectrodes. Twitch and tetanic contractions were elicited by field stimulation. All muscles were fatigued with tetanic contractions at a rate of one contraction per second for 3 min while being exposed to 3 mmole l-1 K0+. During fatigue development the resting potential decreased by 16 mV (control group and pH0 7.2, extracellular pH), while the decrease in the twitch force was 32.8%, compared to 79.3% for the tetanic force, and 84.6% for the maximum rate of force development of the tetanus. Fatigued muscles were also unable to maintain a plateau phase during a tetanus: force declined by 14.8% during this phase. During the recovery period under control conditions (3 mmole l-1 K0+), all four parameters returned to their pre-fatigue values, the recovery of the plateau phase was the fastest (10 min), while that of the twitch force was the slowest (80 min). When K0+ was increased to 7.5 or 9.5 mmole l-1 immediately after fatigue, the recovery rate of the tetanic force and plateau phase was reduced. The maximum rate of force development of the tetanus, however, recovered at a faster rate than control muscles. The recovery of the twitch force was also increased above that of control when K0+ was increased to 9.0 mmole l-1 (a concentration which maximally potentiates the twitch force of unfatigued muscle). Frog sartorius muscles were also tested at pH0 6.4, a pH0 which inhibits force recovery. At that pH0 the effects of K0+ were similar to those observed at pH0 7.2. It is concluded that the role of K+ in muscle fatigue is more complex and may not involve just a contribution to the decrease in force during fatigue development, but may also contribute to an increase in force development under some conditions.

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Extracellular K+ concentration and K+ Balance of the gastrocnemius muscle of the dog during exercise

Cited by 79 publications

References 20 publications

Plasma potassium changes with high intensity exercise.

Plasma potassium changes with high intensity exercise.

Expression of aquaporin-4 in fast-twitch fibers of mammalian skeletal muscle.

The effect of K+ on the recovery of the twitch and tetanic force following fatigue in the sartorius muscle of the frog, Rana pipiens

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