scholarly journals Buffer power and intracellular pH of frog sartorius muscle

1986 ◽  
Vol 50 (5) ◽  
pp. 837-841 ◽  
Author(s):  
N.A. Curtin
Keyword(s):  
Intracellular Ph ◽  
Sartorius Muscle ◽  
Frog Sartorius Muscle ◽  
Buffer Power ◽  
Frog Sartorius

Is the change in intracellular pH during fatigue large enough to be the main cause of fatigue?

1986 ◽  
Vol 64 (6) ◽  
pp. 764-767 ◽  
Author(s):  
J. M. Renaud ◽  
Y. Allard ◽  
G. W. Mainwood
Keyword(s):  
Intracellular Ph ◽  
Extracellular Ph ◽  
Sartorius Muscle ◽  
Bathing Solution ◽  
Tetanic Contraction ◽  
Tetanic Force ◽  
Fatigue Effect ◽  
Frog Sartorius Muscle ◽  
Stimulation Period ◽  
Frog Sartorius

The intracellular pH of frog sartorius muscles exposed to an extracellular pH 8.0 (25 mM HCO3−, 1% CO2) was 6.9–7.1. Following a fatiguing stimulation period (one tetanic contraction per second for 3 min), the intracellular pH was 6.5–6.7. When similar experiments were repeated with frog sartorius muscles exposed to pH 6.4 (2 mM HCO3−, 1% CO2), the intracellular pH was 6.8–6.9 at rest and 6.3–6.4 following fatigue. So, in both experiments the intracellular pH decreased by 0.4–0.5 pH unit during fatigue. When the CO2 concentration of the bathing solution was increased from 1 to 30%, the intracellular pH of resting muscles decreased from 7.0 to 6.2–6.3. Although the effect of CO2 on the intracellular pH was greater than the fatigue effect, the decrease in tetanic force with CO2 was less than 40%, while during fatigue the tetanic force decreased by at least 70%. Therefore in frog sartorius muscle the decrease in tetanic force during fatigue exceeds the decrease that is expected from just a change in intracellular pH.

Constancy of Axial Spacings in Frog Sartorius Muscle during Contraction

Nature ◽  
1965 ◽  
Vol 206 (4991) ◽  
pp. 1358-1358 ◽  
Author(s):  
H. E. HUXLEY ◽  
W. BROWN ◽  
K. C. HOLMES
Keyword(s):  
Sartorius Muscle ◽  
Frog Sartorius Muscle ◽  
Frog Sartorius

Intracellular pH recovery from lactic acidosis of single skeletal muscle fibres

1988 ◽  
Vol 66 (12) ◽  
pp. 1560-1564 ◽  
Author(s):  
Y. E. Allard
Keyword(s):  
Skeletal Muscle ◽  
Lactic Acid ◽  
Intracellular Ph ◽  
Buffer Capacity ◽  
Ringer Solution ◽  
Sartorius Muscle ◽  
Muscle Fibres ◽  
Diffusion Limited ◽  
Skeletal Muscle Fibres ◽  
Frog Sartorius

Intracellular pH (pHi, measured with H+-selective microelectrodes, in quiescent frog sartorius muscle fibres was 7.29 ± 0.09 (n = 13). Frog muscle fibres were superfused with a modified Ringer solution containing 30 mM HEPES buffer, at extracellular pH (pHo) 7.35. Intracellular pH decreased to 6.45 ± 0.14 (n = 13) following replacement of 30 mM NaCl with sodium lactate (30 mM MES, pHo 6.20). Intracellular pH recovery, upon removal of external lactic acid, depended on the buffer concentration of the modified Ringer solution. The measured values of the pHi recovery rates was 0.06 ± 0.01 ΔpHi/min (n = 5) in 3 mM HEPES and was 0.18 ± 0.06 ΔpHi/min (n = 13) in 30 mM HEPES, pHo 7.35. The Na+–H+ exchange inhibitor amiloride (2 mM) slightly reduced pHi recovery rate. The results indicate that the net proton efflux from lactic acidotic frog skeletal muscle is mainly by lactic acid efflux and is limited by the transmembrane pH gradient which, in turn, depends on the extracellular buffer capacity in the diffusion limited space around the muscle fibres.

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