Ionic Regulation in the Muscle Fibres of Carcinus Maenas

1955 ◽  
Vol 32 (2) ◽  
pp. 383-396
Author(s):  
J. SHAW
Keyword(s):  
Membrane Potential ◽  
Total Concentration ◽  
Carcinus Maenas ◽  
Chloride Ions ◽  
Sartorius Muscle ◽  
Muscle Fibres ◽  
Ion Distribution ◽  
Calcium And Magnesium ◽  
Whole Muscle ◽  
Total Muscle

1. Measurements have been made of the concentrations of potassium, chloride, calcium and magnesium, the conductivity and the membrane potential of single isolated fibres of the carpopodite extensor and flexor muscles of Carcinus maenas. 2. Analyses of whole muscles gave the total concentration of the cations as 224 mM./kg. H2O, of which potassium accounted for 120 mM./kg. and sodium 54 mM./kg. Of the anion fraction chloride only accounted for 54mM./kg. H2O. The analyses of the separated fibres were the same as for the whole muscle. 3. The average specific resistance of the fibres is 56Ω-cm. This represents a concentration of muscle ions of about 200 m.equiv./kg. and the electrolyte content of the muscle is not much more than a third of that of the blood. Between 72 and 91% of the total muscle fibre cations are present in an ionized form. 4. The average membrane potential is 58 mV. The ratios of the concentrations of potassium ions and chloride ions in the blood and muscle fibres suggest that these ions may be passively distributed across the membrane. The low concentration of sodium ions in the fibre probably indicates the operation of a ‘sodium pump’ as has been proposed for vertebrate muscles. The distribution of calcium and magnesium cannot be explained in simple terms. 5. The correspondence between the equilibrium potentials for potassium and chloride ions and the membrane potential suggests that theory of ion distribution put forward by Boyle & Conway for frog's sartorius muscle may also be applicable to Carcinus muscles.

scholarly journals Changes in the Membrane Permeability of Frog's Sartorius Muscle Fibers in Ca-Free EDTA Solution

1963 ◽  
Vol 47 (2) ◽  
pp. 379-392 ◽  
Author(s):  
H. Kimizuka ◽  
K. Koketsu
Keyword(s):  
Membrane Permeability ◽  
Chloride Content ◽  
Chloride Ions ◽  
Sartorius Muscle ◽  
Constant Field ◽  
Sodium Influx ◽  
Sodium Potassium ◽  
Edta Solution ◽  
Frog Sartorius ◽  
Sodium And Potassium

The changes in the membrane permeability to sodium, potassium, and chloride ions as well as the changes in the intracellular concentration of these ions were studied on frog sartorius muscles in Ca-free EDTA solution. It was found that the rate constants for potassium and chloride efflux became almost constant within 10 minutes in the absence of external calcium ions, that for potassium increasing to 1.5 to 2 times normal and that for chloride decreasing about one-half. The sodium influx in Ca-free EDTA solution, between 30 and 40 minutes, was about 4 times that in Ringer's solution. The intracellular sodium and potassium contents did not change appreciably but the intracellular chloride content had increased to about 4 times normal after 40 minutes. By applying the constant field theory to these results, it was concluded that (a) PCl did not change appreciably whereas PK decreased to a level that, in the interval between 10 and 40 minutes, was about one-half normal, (b) PNa increased until between 30 and 40 minutes it was about 8 times normal. The low value of the membrane potential between 30 and 40 minutes was explained in terms of the changes in the membrane permeability and the intracellular ion concentrations. The mechanism for membrane depolarization in this solution was briefly discussed.

The resting membrane potential of white muscle from brown trout (Salmo trutta) exposed to copper in soft, acidic water

2000 ◽  
Vol 203 (14) ◽  
pp. 2229-2236 ◽  
Author(s):  
M.W. Beaumont ◽  
E.W. Taylor ◽  
P.J. Butler
Keyword(s):  
Membrane Potential ◽  
Brown Trout ◽  
Salmo Trutta ◽  
White Muscle ◽  
Low Ph ◽  
Ammonium Ion ◽  
Muscle Membrane ◽  
Resting Membrane Potential ◽  
Muscle Fibres ◽  
Brown Trout Salmo Trutta

Previously, the distribution of ammonia between the intracellular and extracellular compartments has been used to predict a significant depolarisation of the resting membrane potential (E(M)) of white muscle from brown trout (Salmo trutta) exposed to a sub-lethal combination of copper and low pH. However, this prediction is based upon two assumptions (i) a relatively high membrane permeability for the ammonium ion with respect to that for ammonia gas and (ii) that this is unaltered by exposure to copper and low pH. Since there is conflicting evidence in the literature of the validity of these assumptions, in the present study E(M) was directly measured in white muscle fibres of trout exposed to copper and low pH (E(M)=−52.2+/−4.9 mV) and compared with that of unexposed, control animals (E(M)=−86.5+/−2.9 mV) (means +/− s.e.m., N=6). In confirming the predicted depolarisation, these data support the hypothesis of electrophysiological impairment as a factor in the reduction in the swimming performance of trout exposed to these pollutants. In addition, the results of this study support the role of a significant permeability of the muscle membrane to NH(4)(+) in determining the distribution of ammonia in fish.

Muscle morphology heterogeneity: control, significance for performance and responses to training

2004 ◽  
Vol 32 ◽  
pp. 11-25
Author(s):  
J L L Rivero
Keyword(s):  
Skeletal Muscle ◽  
Muscle Blood Flow ◽  
Adaptive Plasticity ◽  
Muscle Fibres ◽  
The Past ◽  
Skeletal Musculature ◽  
Skeletal Muscle Fibres ◽  
Exercise And Training ◽  
And Training ◽  
Total Muscle

The skeletal musculature of the horse is highly developed and adapted to match the animal's athletic potential. More than half of a mature horse's body weight comprises skeletal muscle and the total muscle blood flow during maximal exercise represents 78% of total cardiac output. Exercise requires the co–ordinated application of many different body systems under the control of the nervous systems. Metabolites and oxygen reach skeletal muscle fibres via the respiratory, cardiovascular and haematological systems. The muscle fibres produce energy in the form of ATP that, via the contractile machinery, is converted into mechanical work. The structural arrangements of the musculoskeletal system provides the means with which to harness this energy to move the horse's limbs in a characteristic rhythmical pattern that is well established for each gait.Equine skeletal muscle is considerably heterogeneous and this diversity reflects functional specialisation and is the basis of its adaptive plasticity. Cellular and molecular diversity of equine muscle and the response of this tissue to exercise and training have been studied extensively over the past 30 years.

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.

The Motor Innervation and Musculature of the Antennule of the Hermit Crab, Pagurus Alaskensis (Benedict)

1973 ◽  
Vol 58 (3) ◽  
pp. 767-784
Author(s):  
P. J. SNOW
Keyword(s):  
Hermit Crab ◽  
Muscle Tension ◽  
Low Frequency ◽  
Muscle Fibres ◽  
Intracellular Recordings ◽  
Motor Innervation ◽  
Postsynaptic Inhibition ◽  
Tonic Component ◽  
Whole Muscle ◽  
Tonic Tension

1. The motor innervation and musculature of the medial and distal segments of the hermit-crab antennule have been described anatomically. 2. Intracellular recordings within these muscles and simultaneous monitoring of whole-muscle tension have been used to define the motoneurones and contractile properties of the muscle fibres they innervate. 3. The motor system consists of two fast, two slow and one mixed muscle which are innervated by seven motoneurones. 4. The motor innervation is such that this system may be divided into three components: phasic, phasic-tonic and tonic. The possible involvement of these components in the antennular activities is discussed. 5. The tonic component is adapted to produce fine tonic tension in response to relatively low-frequency (5-10/sec) motoneurone discharge. It is suggested that this may be important for the postural control of appendages which, owing to the density of the environmental medium, are relatively weightless. 6. No evidence of postsynaptic inhibition was found, and this is discussed in relation to the movements of the antennule.

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