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![Effects of temperature on ionic components of muscle membrane conductence için kapak resmi Effects of temperature on ionic components of muscle membrane conductence için kapak resmi](/client/assets/d79c3e4af2b6d196/ctx/images/no_image.png)
Effects of temperature on ionic components of muscle membrane conductence
Başlık:
Effects of temperature on ionic components of muscle membrane conductence
Yazar:
Chiu, Tsai-Hsien, author.
ISBN:
9780438057326
Yazar Ek Girişi:
Fiziksel Tanımlama:
1 electronic resource (152 pages)
Genel Not:
Source: Dissertation Abstracts International, Volume: 76-08C.
Advisors: O. F. Hutter.
Özet:
The temperature dependence of the principal ionic components of the resting membrane conductance has been investigated in amphibian and mammalian skeletal muscle with the aim of resolving discrepancies in the literature. In mammalian muscle, the intracellular chloride activities were also measured at two different temperatures. I. FROG SARTORIUS MUSCLE 1. The potassium conductance, GK, was measured on muscles equilibrated in isotonic potassium methylsulphate solution. An average value of 1131 +/- 80 mumho cm-2 (n = 8) for GK was obtained at the mean temperature of 22.90°C. On the basis of the constant field equation this is equivalent to a value of 2.5 X 10-6 cm/sec for PK, the permeability coefficient for potassium ions. 2. After treatment with formaldehyde, a potent blocking agent of inward rectification, the membrane conductance dropped to 195 +/- 20 mumho cm-2. This residual conductance is the ohmic potassium leak conductance (GL). 3. The Q10 values for GK and GL were found to be 1.45 +/- 0.01 and 1.39 +/- 0.02 respectively. The difference between these two figures is not statistically significant. 4. The chloride conductance, GC1, was investigated on muscles in Rb-Ringer solution, using a voltage clamp technique. Its temperature sensitivity was studied at three different extracellular pH. 5. It is concluded that in frog muscle the temperature sensitivity of the membrane conductance is similar in magnitude whether potassium or chloride ions are largely responsible for carrying the membrane current and that no great difference exists in the Q10 of the chloride conductance at different pH. 6. The low value of the Q10 of GC1 and its relative constancy at different pH are at variance with the values for the Q10 of PC1 obtained by determination of 36Cl efflux at different temperatures. Possible explanations for this discrepancy are discussed. 7. The Q10 values of the rate constant for the decay of chloride conductance at pH 7.4 and 9.8 are 2.57 +/- 0.17 and 2.32 +/- 0.01, respectively. The difference between these two values is not statistically significant. These Q10s indicate that for the chloride conductance as for other ionic conductances, the temperature sensitivity of the gating process is higher than the temperature sensitivity of the conductance. II. MAMMALIAN MUSCLE 1. The space constant, lambda, and the membrane conductance, Gm, of rat pectoralis muscle fibres were measured in normal Krebs' solution. At 36-37°C, the mean value for lambda was 0.9 mm, that of Gm 1704 mumho cm-2. 2. On the basis of a sampling method, an increase in membrane conductance was observed when the temperature was lowered. The Q10 of Gm was found to be 0.82. To avoid possible errors caused by the variability of the diameter in different fibres, the temperature sensitivity of Gm was also measured in individual fibres. A Q10 value of 0.84 +/- 0.01 for Gm in Krebs' solution was found in that series. This anomalous behaviour of the membrane conductance of rat pectoralis muscle is consistent with the findings of previous workers using other mammalian muscles. 3. The temperature dependence of GK was measured on muscles immersed in Cl-free solution. A Q10 value of 1.33 (based on sampling) and of 1.36 (based on the same fibre) for GK were obtained. These results indicate that the increase in membrane conductance on cooling does not reside in the potassium component of the membrane conductance. 4. From the input resistances of fibres in Krebs' solution and in chloride free solution at two different temperatures, the contribution of potassium conductance (GK) and chloride conductance (GC1) to the total resting membrane conductance was determined under warm and cold conditions. At 25°C, the GC1/GK ratio is 13.1 and the resting chloride conductance accounts for 93% of the total resting conductance. At 36.6°C, the GC1/GK ratio is 6.9 and the resting chloride conductance accounts for 87% of the total resting conductance.
Notlar:
School code: 0547
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Yer Numarası | Demirbaş Numarası | Shelf Location | Lokasyon / Statüsü / İade Tarihi |
---|---|---|---|
XX(684591.1) | 684591-1001 | Proquest E-Tez Koleksiyonu | Arıyor... |
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