Sehlin J
Am J Physiol. 1981 Jan;240(1):C35-8. doi: 10.1152/ajpcell.1981.240.1.C35.
Accumulation of 45Ca2+ by a microsomal fraction from pancreatic beta-cells of obese-hyperglycemic (ob/ob) mice was stimulated by Mg2+ in a concentration-dependent manner when 2 mM ATP was present. Maximum effect was reached at 2 mM Mg2+. Increasing the Na+ concentration from 20 to 115 mM had no significant effect, but K+ (10-123 mM) stimulated 45Ca2+ accumulation markedly when tested in the presence of 2 mM Mg2+. This effect was not due to changes of osmolarity, ionic strength, or the concentration of Cl-. Stimulation by K+ was drastically reduced on omission of Mg2+ from the incubation medium. K+ did not significantly affect 45Ca2+ uptake by a mitochondria-rich fraction of ob/ob mouse islets. It is suggested that K+ may be involved in modifying the subcellular distribution of calcium ions in pancreatic beta-cells.
当存在2 mM ATP时，肥胖高血糖（ob/ob）小鼠胰腺β细胞微粒体部分对45Ca2+的积累受到Mg2+的浓度依赖性刺激。在2 mM Mg2+时达到最大效应。将Na+浓度从20 mM增加到115 mM没有显著影响，但在2 mM Mg2+存在下测试时，K+（10 - 123 mM）显著刺激45Ca2+积累。这种效应不是由于渗透压、离子强度或Cl-浓度的变化。从孵育培养基中省略Mg2+时，K+的刺激作用急剧降低。K+对ob/ob小鼠胰岛富含线粒体的部分摄取45Ca2+没有显著影响。提示K+可能参与调节胰腺β细胞中钙离子的亚细胞分布。
