scholarly journals Optical measurements of intracellular pH and magnesium in frog skeletal muscle fibres

1982 ◽  
Vol 331 (1) ◽  
pp. 105-137 ◽  
Author(s):  
S. M. Baylor ◽  
W. K. Chandler ◽  
M. W. Marshall
1988 ◽  
Vol 66 (12) ◽  
pp. 1560-1564 ◽  
Author(s):  
Y. E. Allard

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.


1982 ◽  
Vol 37 (7-8) ◽  
pp. 707-708
Author(s):  
Michael Gomolla ◽  
Gernot Gottschalk ◽  
Hans-Christoph Lüttgau

Abstract In single skeletal muscle Fibres perchlorate causes a large shift of the potential dependence of contraction activation to more negative potentials without a corresponding alteration in the kinetics of the inactivation process.


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