scholarly journals Some Factors Affecting the Time Course of the Recovery of Contracture Ability Following a Potassium Contracture in Frog Striated Muscle

1965 ◽  
Vol 48 (6) ◽  
pp. 975-983 ◽  
Author(s):  
J. V. Milligan ◽  
C. Edwards
Keyword(s):  
Recovery Rate ◽  
Time Course ◽  
Calcium Concentration ◽  
Striated Muscle ◽  
Free Solution ◽  
Chemical Binding ◽  
Factors Affecting ◽  
Temperature Changes ◽  
Potassium Contracture ◽  
External Calcium

The recovery rate of contracture ability after a K contracture was shown to be initially dependent upon the rate of repolarization and later to be dependent upon a process which was sensitive to concentration and temperature changes in a manner consistent with chemical binding. It was shown qualitatively that repolarization did not depend on the presence of external calcium and the second process was studied by allowing the muscle to repolarize for 2 minutes in calcium-free solution following a K contracture. Recovery after this procedure was speeded by decreasing either the concentration of potassium in the contracture solution or its temperature and was slowed by either decreasing the calcium concentration of the recovery solution or its temperature or by increasing the duration of the exposure to potassium.

The Effect of Changed Extracellular Calcium and Sodium Concentration on the Electroretinogram of the Crayfish Retina

1980 ◽  
Vol 35 (3-4) ◽  
pp. 308-318 ◽  
Author(s):  
H. Stieve ◽  
I. Claßen-Linke
Keyword(s):  
Dark Adaptation ◽  
Time Course ◽  
Calcium Concentration ◽  
Light Adaptation ◽  
Sodium Concentration ◽  
Strong Increase ◽  
Calcium Stores ◽  
Half Time ◽  
Astacus Leptodactylus ◽  
External Calcium

Abstract The electroretinogram (ERG) of the isolated retina of the crayfish Astacus leptodactylus evoked by strong 10 ms light flashes at constant 5 min intervals was measured while the retina was continuously superfused with various salines which differed in Ca2+ -and Na+ -concentrations. The osmotic pressure of test- and reference-saline was adjusted to be identical by adding sucrose. Results: 1. Upon raising the calcium-concentration of the superfusate in the range of 20-150 mmol/l (constant Na+ -concentration: 208 mmol/l) the peak amplitude hmax and the half time of decay t2 of the ERG both decrease gradually up to about 50% in respect to the corresponding value in reference saline. 2. The recovery of the ERG due to dark adaptation following the “weakly light adapted state” is greatly diminished in high external [Ca2+]ex. 3. Lowering the external calcium-concentration (10 →1 mmol/l) causes a small increase in hmax and a strong increase of the half time of decay t2 (about 180%). Upon lowering the calcium concentration of the superfusate to about 1 nmol/l by 1 mmol/l of the calcium buffer EDTA, a slowly augmenting diminution of the ERG height hm SLX occurs. How­ever, a strong retardation of the falling phase of the ERG characterized by an increase in t2 occurs quickly. Even after 90 min stay in the low calcium saline the retina is still not inexcitable; hmax is 5 - 10% of the reference value. The diminution of hmax occurs about six-fold faster when the buffer concentration is raised to 10 mmol/l EDTA. 4. Additional lowering of the Na+ -concentration (208 →20.8 mmol/l) in a superfusate with a calcium concentration raised to 150 mmol/l causes a strong reduction of the ERG amplitude hmax to about 10%. 5. In a superfusate containing 1 nmol/l calcium such lowering of the sodium concentration (208 → 20.8 mmol/l) causes a diminution of the ERG height to about 40% and the shape of the ERG to become polyphasic; at least two maxima with different time to peak values are observed. Interpretation: 1. The similarity of effects, namely raising external calcium concentration and light adaptation on the one hand and lowering external calcium and dark adaptation on the other hand may indicate that the external calcium is acting on the adaptation mechanism of the photoreceptor cells, presumably by influencing the intracellular [Ca2+]. 2. The great tolerance of the retina against Ca2+ -deficiency in the superfusate might be effected by calcium stores in the retina which need high Ca2+ -buffer concentrations in the superfusate to become exhausted. 3. In contrast to the Limulus ventral nerve photoreceptor there does not seem to be an antagonis­ tic effect of sodium and calcium in the crayfish retina on the control of the light channels. 4. The crayfish receptor potential seems to be composed of at least two different processes. Lowering calcium-and lowering external sodium-concentration both diminish the height and change the time course of the two components to a different degree. This could be caused by in­ fluencing the state of adaptation and thereby making the two maxima separately visible.

scholarly journals The Time Course of the Loss and Recovery of Contracture Ability in Frog Striated Muscle Following Exposure to Ca-Free Solutions

1965 ◽  
Vol 48 (5) ◽  
pp. 841-858 ◽  
Author(s):  
J. V. Milligan
Keyword(s):  
Diffusion Coefficient ◽  
Calcium Ion ◽  
Time Course ◽  
Striated Muscle ◽  
Potassium Concentration ◽  
Ion Concentration ◽  
Bathing Solution ◽  
Free Solution ◽  
K Concentration ◽  
Calcium Ion Concentration

Using area under the contracture curve to quantitate contractures, the diffusion coefficient of calcium ions within the frog toe muscle during washout in a calcium-free solution and subsequent recovery after reintroduction of calcium to the bathing solution was calculated to be about 2 x 10-6 cm2/sec. The diffusion coefficient measured during washout was found to be independent of temperature or initial calcium ion concentration. During recovery it was found to decrease if the temperature was lowered. This was likely due to the repolarization occurring after the depolarizing effect of the calcium-free solution. The relation between contracture area and [Ca]o was found to be useful over a wider range than that between maximum tension and [Ca]o. The normalized contracture areas were larger at lower calcium concentrations if the contractures were produced with cold potassium solutions or if NO3 replaced Cl in the bathing solutions. Decreasing the potassium concentration of the contracture solution to 50 mM from 115 mM did not change the relation between [Ca]o and the normalized area. If the K concentration of the bathing solution was increased, the areas were decreased at lower concentrations of Ca.

scholarly journals Interactions of Calcium with Sodium and Potassium in Membrane Potentials of the Lobster Giant Axon

1960 ◽  
Vol 43 (3) ◽  
pp. 609-619 ◽  
Author(s):  
W. J. Adelman ◽  
J. C. Dalton
Keyword(s):  
Time Course ◽  
Calcium Concentration ◽  
Giant Axon ◽  
Ion Concentration ◽  
Simultaneous Removal ◽  
Spike Amplitude ◽  
Low Sodium ◽  
Low Calcium ◽  
Sodium And Potassium ◽  
External Calcium

Experiments were performed on the lobster giant axon to determine the relation between intracellular spike amplitude and external calcium ion concentration. Action potential decline in low external calcium is greatly accelerated by simultaneous removal of external sodium ion. Correlation of the time course of spike decline in low calcium-low sodium solution with the time courses of spike decline in low calcium alone and in low sodium alone indicates that the effect of simultaneous removal of both ions is significantly greater than the sum of the individual effects. For a given time of treatment, spike amplitude was a function of external calcium concentration. While spike height is proportional to the log of the external calcium concentration over the range 2.5 to 50 millimolar, the proportionality constant is dependent upon the sodium concentration. Under the conditions of low external sodium (50 per cent reduction) the slope of the linear relationship between the spike height and the log of the external calcium concentration is about 5 times greater than in normal external sodium. Decreasing external calcium concentration and simultaneously increasing external potassium concentration produce a greater spike reduction than the arithmetic sum of spike reductions in low calcium alone and in high potassium alone. It is suggested that calcium interacts strongly with sodium and potassium in the spike-generating mechanism. A theoretical basis for these results is discussed.

Calcium and Contraction in the Rabbit Anterior Mesenteric–Portal Vein

1972 ◽  
Vol 50 (4) ◽  
pp. 289-299 ◽  
Author(s):  
G. A. Collins ◽  
M. C. Sutter ◽  
J. C. Teiser
Keyword(s):  
Portal Vein ◽  
Membrane Permeability ◽  
Time Course ◽  
Contractile Response ◽  
Calcium Influx ◽  
Contractile Activity ◽  
Krebs Solution ◽  
Free Solution ◽  
Membrane Bound ◽  
External Calcium

Studies were done measuring contractile activity in the isolated rabbit anterior mesenteric–portal vein (A.M.V.). The rabbit A.M.V. requires external calcium for both spontaneous activity and the initiation and maintenance of contractions to agonists.After bathing the tissues in calcium-free Krebs' solution containing 1 mM ethyleneglycoltetraacetic acid (EGTA) for 10 min, and then washing out the EGTA, the re-addition of calcium produced a contraction. The pre-addition of a small amount of calcium (0.1 mM) after EGTA treatment (while not inducing a contractile response) alters subsequent contractile responses to larger concentrations of calcium. This is interpreted as the ability of membrane-bound calcium to control membrane permeability to calcium.Other experiments involved bathing the tissues in calcium-free solution until no response was obtained to agonists, and then re-adding calcium. The time course of the responses to noradrenaline after calcium re-addition depended on the length of calcium incubation. This suggests that noradrenaline can release a loosely bound calcium fraction which may be involved in controlling calcium influx. This bound calcium, however, does not provide a major source of activator calcium in normal Krebs' solution.

scholarly journals Expressed Na channel clones differ in their sensitivity to external calcium concentration

1992 ◽  
Vol 62 (1) ◽  
pp. 37-40 ◽  
Author(s):  
M. Chahine ◽  
L.Q. Chen ◽  
R.G. Kallen ◽  
R.L. Barchi ◽  
R. Horn
Keyword(s):  
Calcium Concentration ◽  
Na Channel ◽  
External Calcium

scholarly journals Factors affecting the appearance of the hump charge movement component in frog cut twitch fibers.

1991 ◽  
Vol 98 (2) ◽  
pp. 315-347 ◽  
Author(s):  
C S Hui
Keyword(s):  
Time Course ◽  
Extreme Case ◽  
Complete Recovery ◽  
Creatine Phosphate ◽  
Boltzmann Distribution ◽  
Distribution Functions ◽  
Charge Movement ◽  
Factors Affecting ◽  
Gap Technique ◽  
Voltage Dependent

Charge movement was measured in frog cut twitch fibers with the double Vaseline gap technique. Five manipulations listed below were applied to investigate their effects on the hump component (I gamma) in the ON segments of TEST minus CONTROL current traces. When external Cl-1 was replaced by MeSO3- to eliminate Cl current, I gamma peaked earlier due to a few millivolts shift of the voltage dependence of I gamma kinetics in the negative direction. The Q-V plots in the TEA.Cl and TEA.MeSO3 solutions were well fitted by a sum of two Boltzmann distribution functions. The more steeply voltage-dependent component (Q gamma) had a V approximately 6 mV more negative in the TEA.MeSO3 solution than in the TEA.Cl solution. These voltage shifts were partially reversible. When creatine phosphate in the end pool solution was removed, the I gamma hump disappeared slowly over the course of 20-30 min, partly due to a suppression of Q gamma. The hump reappeared when creatine phosphate was restored. When 0.2-1.0 mM Cd2+ was added to the center pool solution to block inward Ca current, the I gamma hump became less prominent due to a prolongation in the time course of I gamma but not to a suppression of Q gamma. When the holding potential was changed from -90 to -120 mV, the amplitude of I beta was increased, thereby obscuring the I gamma hump. Finally, when a cut fiber was stimulated repetitively, I gamma lost its hump appearance because its time course was prolonged. In an extreme case, a 5-min resting interval was insufficient for a complete recovery of the waveform. In general, a stimulation rate of once per minute had a negligible effect on the shape of I gamma. Of the five manipulations, MeSO3- has the least perturbation on the appearance of I gamma and is potentially a better substitute for Cl- than SO2-(4) in eliminating Cl current if the appearance of the I gamma hump is to be preserved.

The resting membrane potential of Drosophila melanogaster larval muscle depends strongly on external calcium concentration

2010 ◽  
Vol 56 (3) ◽  
pp. 304-313 ◽  
Author(s):  
Jacob L. Krans ◽  
Karen D. Parfitt ◽  
Kristin D. Gawera ◽  
Patricia K. Rivlin ◽  
Ronald R. Hoy
Keyword(s):  
Drosophila Melanogaster ◽  
Membrane Potential ◽  
Calcium Concentration ◽  
Resting Membrane Potential ◽  
Larval Muscle ◽  
External Calcium
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