THE RELATION BETWEEN Z-DISK LATTICE SPACING AND SARCOMERE LENGTH IN SARTORIUS MUSCLE FIBRES FROM HYLA CERULEA

1976 ◽  
Vol 54 (5) ◽  
pp. 441-447 ◽  
Author(s):  
DF Davey
Keyword(s):  
Lattice Spacing ◽  
Sarcomere Length ◽  
Sartorius Muscle ◽  
Muscle Fibres

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.

An Electron Microscopic Study of the Muscle-fibres of the Diaphragm

1951 ◽  
Vol s3-92 (19) ◽  
pp. 323-332
Author(s):  
M. M. BLUHM ◽  
C. SITARAMAYYA
Keyword(s):  
Sarcomere Length ◽  
Muscle Fibres ◽  
Striated Muscles ◽  
Rat Diaphragm ◽  
Electron Microscopic ◽  
Adult Type ◽  
Isotonic Contraction ◽  
Acetyl Choline ◽  
Adult Rat ◽  
Passive Stretching

Myofibrils of rat diaphragm of various ages, in different states of activity, after denervation, and after acetyl choline contracture, were studied by electron microscopy. A comparative study of other rodent diaphragms and of human diaphragm was also made. Myofibrils from diaphragm are similar to those of other striated muscles. The differentiation into A and I bands is due to differences in the substance present round the actomyosin filaments in those regions. The Z disk is extra-sarcomere; it-appears even before any differentiation of the fibril into A and I bands is recognizable. At the age of about 42 days, the myofibrils in rat diaphragm are completely differentiated and conform tothe adult type. The sarcomere length in adult rat diaphragm is between 2 and 3 µ. The adult rat diaphragm contains two types of fibrils which differ, though not sharply, in their extensibility and thickness. The A and I bands react differently to a variety of stimuli. Thus, passive stretching affects the I band almost exclusively, while contraction affects both bands; here, again, the effect depends on the type of contraction; isotonic contraction shortens both A and I, whereas isometric contraction shortens A and lengthens I. In the denervated muscle the A band is shortened. On thewhole, the A band seems to play the major role in contraction. The H disk is intra-sarcomere and appears during contraction, especially when the muscle is stimulated in the stretched state. The M and N lines also are intra-sarcomere. Evidence regarding their nature and appearance is discussed.

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