Electron emission from 57Fe nuclei excited with synchrotron radiation

The increase in cytosolic free Ca2+ concentration ([Ca2+]i) seen in submandibular cells of early postnatal rats following exposure to acetylcholine (ACh) is larger than in cells of adult rats. To elucidate possible reasons for this difference, we compared Ca2+ movements through Ca2+ pumps in both types of cells using Ca(2+)-sensitive fluorescent probe fura-2 and the radiotracer 45Ca2+. Ca2+ release induced by endoplasmic reticulum (ER) Ca(2+)-pump inhibitor thapsigargin (TG) was significantly smaller in neonatal cells than in adult cells, whereas the inositol 1,4,5-trisphosphate (IP3)-elicited Ca2+ release was comparable in both cell types. This suggests that although the size of the IP3-sensitive Ca2+ pool is adequate in immature cells, the activity of TG-sensitive Ca2+ pump in this pool is lower. The activity of the plasma membrane (PM) Ca(2+)-pump, measured by extrusion of 45Ca2+, was also significantly lower in immature cells. These results indicate that both ER and PM Ca2+ pumps may be functionally underdeveloped in immature cells, and that the enhanced increase of [Ca2+]i seen in response to ACh in immature cells may be partially, if not completely, due to a reduced capacity for removal of Ca2+ from the cytosol by active mechanisms.     

稳定核激发态的奇特结构

在相对论平均场理论框架下,利用壳模型方法处理对关联,研究17N和18O基态和激发态性质,计算17N和18O基态和激发态的中子和质子方均根半径,给出中子和质子的密度分布.结果表明:这些核的激发态半径比基态大,中子密度具有更大的空间分布,形成了类晕或皮的奇特结构.