Intracellular Calcium

It is a well established fact that intracellular calcium concentrations are extremely important for cell function. This article looks specifically at calcium stores in skeletal muscle. Evidence has indicated that calcium stores in the sarcoplasmic reticulum (SR) are replenished with extracellular calcium by some unknown mechanism. It is hypothesized that the calcium is entering through a channel on the plasma membrane. The aim of this study was to find the current caused by this calcium influx. The researchers monitored intracellular and whole cell voltages and used a fluorescent dye to track the calcium. Surprisingly, they were not able to find anything that would indicate a SR store dependent calcium influx. Based on these results, they believe that there might not be any calcium influx that solely depends on SR store levels and that the SR stores are replenished with cytoplasmic calcium that entered the cell independently. Unfortunately, their results are inconclusive and the controversy continues.