Newbold R P, Tume R K
Aust J Biol Sci. 1977 Dec;30(6):519-26. doi: 10.1071/bi9770519.
The cold-induced release of calcium from sarcoplasmic reticulum preparations from both white and red muscles of the rabbit was studied. Part of the release was due to the increase in pH of the reaction mixture with cooling. Calcium release was greatly reduced or completely prevented by the inclusion of oxalate or inorganic orthophosphate in the medium. No release occurred in 5 mM oxalate. With phosphate, the proportion of the calcium previously taken up at 23 degrees C that was released at 0 degrees C became progressively smaller as the phosphate concentration was increased. When the pH was adjusted to be the same at 0 degrees C as at 23 degrees C there was little release from white muscle preparations in 10 mM phosphate and no release when the phosphate concentration was 20 mM or more. With red muscle preparations calcium was released at higher phosphate concentrations, 8% of the amount previously taken up still being released at 50 mM phosphate and a smaller amount at 100 mM phosphate. The effects of oxalate and phosphate can be explained in terms of the reduction in free calcium concentration inside the vesicles by calcium precipitants, and a difference in the temperature coefficients of calcium inflow and outflow.
对兔的白色和红色肌肉肌浆网制剂进行了冷诱导钙释放的研究。部分释放是由于反应混合物冷却时pH值升高所致。通过在培养基中加入草酸盐或无机正磷酸盐，钙释放大大减少或完全被阻止。在5 mM草酸盐中不发生释放。对于磷酸盐，随着磷酸盐浓度增加，先前在23℃摄取的钙在0℃释放的比例逐渐变小。当将0℃时的pH值调节至与23℃时相同，在10 mM磷酸盐中白色肌肉制剂几乎不释放，当磷酸盐浓度为20 mM或更高时则无释放。对于红色肌肉制剂，在较高磷酸盐浓度下钙会释放，在50 mM磷酸盐时仍有8%先前摄取的量被释放，在100 mM磷酸盐时释放量较少。草酸盐和磷酸盐的作用可以通过钙沉淀剂降低囊泡内游离钙浓度以及钙流入和流出的温度系数差异来解释。
