Blom E, Ali M M, Mortensen B, Huseby N E
Tromsø College, Faculty of Health Sciences, Norway.
Clin Chim Acta. 1998 Feb 23;270(2):125-37. doi: 10.1016/s0009-8981(97)00217-9.
Three isoforms of human alkaline phosphatase (liver, bone and placental ALP) were purified and their elimination studied after intravenous injection in rats. The rates of elimination were significantly inhibited by prior injection of asialofetuin, indicating that the uptake was mediated by the galactose receptor in liver. Their relative clearance rates differed, being rapid for the bone ALP, significantly slower for the liver isoform and very slow for the placental ALP. The bone ALP showed a rapid initial clearance, apparently related to its large glycan heterogeneity and to the presence of molecules with a low sialic acid content. When isolated from serum the liver and bone ALP isoforms showed clearance rates differing slightly from those of the organ derived forms. We conclude that differences in carbohydrate structure and amount of sialic acid of the three isoforms result in various clearance rates. These differences will also affect their serum concentrations as well as the composition and heterogeneity of the individual isoforms in serum.
纯化了人碱性磷酸酶的三种同工型（肝、骨和胎盘碱性磷酸酶），并在大鼠静脉注射后研究了它们的消除情况。预先注射去唾液酸胎球蛋白可显著抑制消除速率，这表明摄取是由肝脏中的半乳糖受体介导的。它们的相对清除率有所不同，骨碱性磷酸酶的清除速度很快，肝脏同工型明显较慢，胎盘碱性磷酸酶则非常慢。骨碱性磷酸酶显示出快速的初始清除，这显然与其高度的聚糖异质性以及低唾液酸含量分子的存在有关。当从血清中分离时，肝脏和骨碱性磷酸酶同工型的清除率与器官来源形式的清除率略有不同。我们得出结论，三种同工型的碳水化合物结构和唾液酸含量的差异导致了不同的清除率。这些差异也将影响它们的血清浓度以及血清中各个同工型的组成和异质性。
