Binding of calcium ions to cell membrane isolated from bullfrog skeletal muscle

1964 ◽  
Vol 207 (2) ◽  
pp. 509-512 ◽  
Author(s):  
K. Koketsu ◽  
R. Kitamura ◽  
R. Tanaka
Keyword(s):  
Skeletal Muscle ◽  
Membrane Potential ◽  
Cell Membrane ◽  
Membrane Permeability ◽  
Calcium Ions ◽  
Cytoplasmic Membrane ◽  
Muscle Fibers ◽  
Potassium Ions ◽  
Chloroform Methanol ◽  
Sodium And Potassium

The membrane fragments of bullfrog skeletal muscle fibers were isolated by a modification of the method of Kono and Colowick (1961). Radiocalcium ions were bound to these isolated membrane fragments, and the binding of calcium ions was impeded by both sodium and potassium ions. The extractable portion of the isolated membrane fragments with chloroform-methanol mixture bound calcium ions whereas no appreciable binding of calcium ions was observed with the extracted residue. The results suggested that the binding of calcium ions takes place on the lipid or lipoprotein of the so-called cytoplasmic membrane which plays an important role in regulating the membrane permeability and the membrane potential.

scholarly journals Calcium Sparks in Intact Skeletal Muscle Fibers of the Frog

2001 ◽  
Vol 118 (6) ◽  
pp. 653-678 ◽  
Author(s):  
S. Hollingworth ◽  
J. Peet ◽  
W.K Chandler ◽  
S.M. Baylor
Keyword(s):  
Skeletal Muscle ◽  
Membrane Potential ◽  
Rise Time ◽  
Rana Temporaria ◽  
Muscle Fibers ◽  
Fluorescence Decay ◽  
Half Maximum ◽  
Calcium Sparks ◽  
Mean Values ◽  
Skeletal Muscle Fibers

Calcium sparks were studied in frog intact skeletal muscle fibers using a home-built confocal scanner whose point-spread function was estimated to be ∼0.21 μm in x and y and ∼0.51 μm in z. Observations were made at 17–20°C on fibers from Rana pipiens and Rana temporaria. Fibers were studied in two external solutions: normal Ringer's ([K+] = 2.5 mM; estimated membrane potential, −80 to −90 mV) and elevated [K+] Ringer's (most frequently, [K+] = 13 mM; estimated membrane potential, −60 to −65 mV). The frequency of sparks was 0.04–0.05 sarcomere−1 s−1 in normal Ringer's; the frequency increased approximately tenfold in 13 mM [K+] Ringer's. Spark properties in each solution were similar for the two species; they were also similar when scanned in the x and the y directions. From fits of standard functional forms to the temporal and spatial profiles of the sparks, the following mean values were estimated for the morphological parameters: rise time, ∼4 ms; peak amplitude, ∼1 ΔF/F (change in fluorescence divided by resting fluorescence); decay time constant, ∼5 ms; full duration at half maximum (FDHM), ∼6 ms; late offset, ∼0.01 ΔF/F; full width at half maximum (FWHM), ∼1.0 μm; mass (calculated as amplitude × 1.206 × FWHM3), 1.3–1.9 μm3. Although the rise time is similar to that measured previously in frog cut fibers (5–6 ms; 17–23°C), cut fiber sparks have a longer duration (FDHM, 9–15 ms), a wider extent (FWHM, 1.3–2.3 μm), and a strikingly larger mass (by 3–10-fold). Possible explanations for the increase in mass in cut fibers are a reduction in the Ca2+ buffering power of myoplasm in cut fibers and an increase in the flux of Ca2+ during release.

Oxygen free radicals affect cardiac and skeletal cell membrane potential during hemorrhagic shock in rats

1992 ◽  
Vol 262 (1) ◽  
pp. H84-H90
Author(s):  
J. Yokota ◽  
J. J. Chiao ◽  
G. T. Shires
Keyword(s):  
Skeletal Muscle ◽  
Blood Flow ◽  
Membrane Potential ◽  
Cell Membrane ◽  
Hemorrhagic Shock ◽  
Organ Blood Flow ◽  
Atp Content ◽  
Shed Blood ◽  
Excitable Cell ◽  
Significant Difference

Oxygen free radical (OFR) damage of excitable cell membranes (heart and skeletal muscle) during hemorrhagic shock and after resuscitation was studied in control rats and in rats pretreated with superoxide dismutase (SOD) and catalase (CAT; 6,000 U each) before hemorrhage. Their mean arterial pressure (MAP) was lowered to and maintained at 45 mmHg until 30% of the shed blood was spontaneously reinfused. The remaining blood and twice that volume of lactated Ringer solution were then infused. Cardiac output and organ blood flow were measured by the microsphere technique. The resting membrane potential (Em) and tissue ATP content in the heart and skeletal muscle were determined. There was no significant difference between the control and SOD + CAT groups in shock duration, maximal shed blood, hemodynamics, regional blood flow, or in ATP content in both heart and skeletal muscle, both during shock and after resuscitation. Radical scavenger treatment did not prevent muscle depolarization during shock. After resuscitation, however, significant repolarization in hearts and skeletal muscle of the SOD + CAT group (heart, -70.0 +/- 1.1; muscle, -87.0 +/- 0.6 mV) was noted when compared with the controls (heart, -62.5 +/- 1.2; muscle, -82.7 +/- 1.1 mV; P less than 0.05). This implicates OFRs as mediators of excitable cell membrane injury following resuscitation.

scholarly journals Clostridium acetobutylicum bacterial membrane responses to carbon ion beam irradiation perturbations

2020 ◽  
Author(s):  
Yue Gao ◽  
Xiang Zhou ◽  
Miaomiao Zhang ◽  
Yajun Liu ◽  
Xiaopeng Guo ◽  
...  
Keyword(s):  
Fatty Acid ◽  
Membrane Potential ◽  
Cell Membrane ◽  
Cell Surface ◽  
Membrane Permeability ◽  
Clostridium Acetobutylicum ◽  
Surface Hydrophobicity ◽  
Cell Membrane Permeability ◽  
Butanol Tolerance ◽  
Butanol Stress

Abstract Background Clostridium acetobutylicum is an important strain during acetone-butanol-ethanol (ABE) fermentation. However, butanol has toxic effects on cells, limiting the application of ABE fermentation. Accordingly, in this study, we aimed to elucidate the metabolic mechanisms through which Clostridium adapts to butanol stress to facilitate the industrial utilization of Clostridium. Results First, using cell morphology, cell membrane permeability and membrane potential, cell surface hydrophobicity, and cell membrane fatty acid composition analyses in wild-type (ATCC 824) and butanol-tolerant (Y217) strains under butanol stress, we explored the responses in the cell membrane to evaluate the damage caused by butanol poisoning. After 2.0% (v/v) butanol treatment, the extracellular conductivity of ATCC 824 increased, intracellular proteins and nucleotides were released in large quantities, the fluorescein diacetate staining rate decreased, the membrane potential decreased, and the cell membrane permeability increased. Under butanol shock, the cell surface of Y217 cells remained intact, and its butanol tolerance mechanism increased the integrity of cell membrane and reduced leakage of cell contents caused by changed in cell membrane permeability, thereby preventing butanol damage to the cell membrane. When stimulated with butanol, Y217 cells showed reduced surface hydrophobicity, thereby improving cellular tolerance to butanol. A comparison of differences in fatty acid compositions between ATCC 824 and Y217 cell membranes under butanol stress further demonstrated that maintenance of the normal physiological characteristics of cell membranes played important roles in resisting the impact of organic solvents. Conclusions Our findings clarified the changes in physiological and biochemical characteristics of the mutant Y217 cell membrane stimulated with butanol to enhance its tolerance. These results may provide important theoretical guidance for further accelerating the acquisition of bacteria with high butanol tolerance and promoting butanol production. Moreover, our study provided a scientific basis for improving the industrial and environmental adaptability of Clostridium.

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