Effects of high extracellular calcium and strontium on inositol polyphosphates in bovine parathyroid cells.
Effects of high extracellular calcium and strontium on inositol polyphosphates in bovine parathyroid cells.
复制标题
高细胞外钙和锶对牛甲状旁腺细胞中肌醇多磷酸的影响。
DOI：
10.1002/jbmr.5650080715
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发表时间：
1993
期刊：
影响因子：
--
通讯作者：
Johnson,RM
中科院分区：
文献类型：
--
作者：
Shoback,DM;Chen,TH;Lattyak,B;King,K;Johnson,RM
The addition of Ca2+or a variety of divalent cations increases intracellular Ca2+in parathyroid cells and suppresses secretion. Since 1,4,5‐inositol trisphosphate (IP3) and 1,3,4,5‐inositol tetrakisphosphate (IP4) mediate Ca2+mobilization in other systems, we examined high Ca2+‐ and Sr2+‐induced accumulation of IP3and IP4isomers by anion‐exchange HPLC and measured 1,4,5‐IP3mass in parathyroid cells. Raising extracellular [Ca2+] from 0.5 to 3.0 mM increased3H‐1,4,5‐IP3within 5 s, which was confirmed by mass measurements.3H‐1,3,4‐IP3rose gradually by 10 s and increased for 60 s after the addition of Ca2+. Although we detected no change in3H‐1,3,4,5‐IP4, the increase in3H‐1,3,4‐IP3suggests that3H‐1,3,4,5‐IP4was being formed. The addition of 4 mM SrCl2produced similar changes in 1,4,5‐IP3, which were confirmed by mass assay.3H‐1,3,4,5‐IP4did not change. However, Sr2+induced a gradual increase in3H‐1,3,4‐IP3, which remained above control levels for 5 minutes. Isotopic labeling studies in this system may underestimate changes in 1,4,5‐IP3mass, but both mass and radioisotopic analyses indicate that high extracellular Ca2+and Sr2+stimulate substantial increases in 1,4,5‐IP3without significant accumulation of 1,3,4,5‐IP4. These studies suggest a role for 1,4,5‐IP3in intracellular Ca2+mobilization by divalent cations in parathyroid cells.
