Enhancement of parathyroid hormone-stimulated bone resorption by poly-L-lysine.
Enhancement of parathyroid hormone-stimulated bone resorption by poly-L-lysine.
复制标题
聚-L-赖氨酸增强甲状旁腺激素刺激的骨吸收。
作者：
L. Raisz;P. Bergmann;J. Dominguez;M. Price
将多聚L赖氨酸加入含牛血清白蛋白的化学限定培养液(BGJ)中，在甲状旁腺激素(PTH)存在和不存在的情况下，将其加入胎鼠骨骼中。通过释放先前结合的45Ca来衡量骨吸收。加入浓度为3-100微克/毫升的磷脂酶II可增强次最大剂量甲状旁腺素对骨吸收的刺激作用，但对对照组未刺激培养的45Ca释放影响不大。高浓度的磷脂酶II对~(45)Ca释放有抑制作用。透析PL II不能改变PL II对PTH的增强或抑制作用。在含血清的培养中，PL II不增加对甲状旁腺素的敏感性。相对分子质量较高的PL II制剂效果较差。PL II对1，25-二羟基维生素D、前列腺素E_2、破骨细胞激活因子或细菌内毒素的吸收反应没有增强作用。PL II选择性增强对低浓度甲状旁腺素的反应的机制尚不清楚，但可能是由于这种碱性多肽能够干扰甲状旁腺激素与激素受体以外的位点的结合，或阻止甲状旁腺激素被骨降解。
Poly-L-lysine (PL II; mol wt, 1000-4000) was added to fetal rat bones cultured in a chemically defined medium (BGJ) containing bovine serum albumin in the presence and absence of parathyroid hormone (PTH). Bone resorption was measured by the release of previously incorporated 45Ca. The addition of PL II at concentrations of 3-100 microgram/ml enhanced the stimulation of bone resorption by submaximal doses of PTH but had little effect on 45Ca release from control unstimulated cultures. Higher concentrations of PL II produced inhibition of 45Ca release. Dialysis of PL II did not alter enhancement or inhibition by PL II. PL II did not increase sensitivity to PTH in serum-supplemented cultures. Higher molecular weight PL II preparations were less effective. PL II did not enhance the resorptive response to 1,25-dihydroxyvitamin D, prostaglandin E2, osteoclast-activating factor, or bacterial endotoxin. The mechanism of the selective ability of PL II to enhance the response to low concentrations of PTH is unknown but may be due to the ability of this basic polypeptide to interfere with binding of PTH to sites other than the hormone receptor or to block degradation of PTH by bone.