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Digitale Medien

Spatial and temporal patterns of intracellular calcium in colonic smooth muscle (1992)

Mayer, Emeran A. ; Kodner, Anatoly ; Sun, Xiao Ping ; [weitere]

Springer

The journal of membrane biology 125 (1992), S. 107-118

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ISSN: 1432-1424

Schlagwort(e): Ca2+ oscillations ; Ca2+ wave ; sarcoplasmic reticulum

Quelle: Springer Online Journal Archives 1860-2000

Thema: Biologie , Chemie und Pharmazie

Notizen: Summary Intracellular calcium [Ca2+] i measurements in cell suspension of gastrointestinal myocytes have suggested a single [Ca2+] i transient followed by a steady-state increase as the characteristic [Ca2+] i response of these cells. In the present study, we used digital video imaging techniques in freshly dispersed myocytes from the rabbit colon, to characterize the spatiotemporal pattern of the [Ca2+] i signal in single cells. The distribution of [Ca2+] i in resting and stimulated cells was nonhomogeneous, with gradients of high [Ca2+] i present in the subplasmalemmal space and in one cell pole. [Ca2+] i gradients within these regions were not constant but showed temporal changes in the form of [Ca2+] i oscillations and spatial changes in the form of [Ca2+] i waves. [Ca2+] i oscillations in unstimulated cells (n = 60) were independent of extracellular [Ca2+] and had a mean frequency of 12.6 +1.1 oscillations per min. The baseline [Ca2+], was 171 ± 13 nm and the mean oscillation amplitude was 194 ± 12 nm. Generation of [Ca2+] i waves was also independent of influx of extracellular Ca2+. [Ca2+] i waves originated in one cell pole and were visualized as propagation mostly along the subplasmalemmal space or occasionally throughout the cytoplasm. The mean velocity was 23 +3 μm per sec (n = 6). Increases of [Ca2+] i induced by different agonists were encoded into changes of baseline [Ca2+] i and the amplitude of oscillations, but not into their frequency. The observed spatiotemporal pattern of [Ca2+] i regulation may be the underlying mechanism for slow wave generation and propagation in this tissue. These findings are consistent with a [Ca2+] i regulation whereby cell regulators modulate the spatiotemporal pattern of intracellularly generated [Ca2+] i oscillations.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF00233351

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Digitale Medien

Study of ion solvation and ion association in polymer gel electrolyte with polyethylene oxide-co-polypropylene oxide as a plasticizer (1996)

Sun, Xiao Guang ; Li, Bin ; Lin, Yun Qing ; [weitere]

New York, NY [u.a.] : Wiley-Blackwell

Polymer International 41 (1996), S. 301-305

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ISSN: 0959-8103

Schlagwort(e): gel electrolyte ; polytriethylene glycol dimethacrylate ; ion solvation ; ion association ; molal conductance ; Chemistry ; Polymer and Materials Science

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie , Maschinenbau , Physik

Notizen: Using a molal conductance method, ion solvation and ion association in polytriethylene glycol dimethacrylate (PTREGD)-LiClO4 gel electrolytes with amorphous ethylene oxide-co-propylene oxide (EO-co-PO, M̄n = 1750) as the plasticizer were investigated. It was found that the fraction of solute existing as single ions (αi) and ion pairs (αp) decreases, while that of triple ions (αt) increases linearly with increasing salt concentration. The dependence of these fractions on molecular weight of plasticizer was also examined. It was shown that αi and αt increase and αp decreases with increasing molecular weight. The result of temperature dependence of these fractions was very interesting: when the temperature is lower than 55°C, αi increases while αp and αt decrease with increasing temperature; however, when the temperature is higher than 55°C, the reverse is true.

Zusätzliches Material: 4 Ill.