Malet P F, Locke C L, Trotman B W, Soloway R D
Hepatology. 1986 Jul-Aug;6(4):569-73. doi: 10.1002/hep.1840060404.
The purpose of this study was to examine the role of calcium ions in gallbladder glycoprotein secretion in cultured guinea pig gallbladder explants. The calcium ionophore A23187 showed a threshold of 2 micrograms per ml medium for stimulation of secretion of [3H]glucosamine-labeled glycoproteins over a 30 min incubation period. The ionophore at 3 and 5 micrograms per ml medium resulted in a 3- to 4-fold increase in secretion of [3H]glucosamine-labeled glycoproteins. Ionophore-induced stimulation of glycoprotein secretion was abolished by the addition of 0.01 mM verapamil to the medium. To study the effect of changes in extracellular calcium on basal glycoprotein secretion, explants were cultured for 24 hr in media with 0.007, 0.5 or 2.0 mM calcium; no differences in basal glycoprotein secretion were observed. When cultured in medium with 1.0 mM EGTA, basal secretion decreased significantly vs. controls in 0.007 mM total calcium medium. Total [3H]glucosamine incorporation by explants in medium with EGTA was unaltered, however, suggesting that the low level of calcium in the medium was selectively impairing the secretory process. These findings indicate that calcium ions are important in the regulation of gallbladder glycoprotein secretion.
本研究的目的是检测钙离子在培养的豚鼠胆囊外植体中胆囊糖蛋白分泌过程中的作用。在30分钟的孵育期内，钙离子载体A23187刺激[3H]葡糖胺标记的糖蛋白分泌的阈值为每毫升培养基2微克。每毫升培养基中3微克和5微克的离子载体导致[3H]葡糖胺标记的糖蛋白分泌增加3至4倍。向培养基中添加0.01 mM维拉帕米可消除离子载体诱导的糖蛋白分泌刺激。为了研究细胞外钙变化对基础糖蛋白分泌的影响，将外植体在含有0.007、0.5或2.0 mM钙的培养基中培养24小时；未观察到基础糖蛋白分泌有差异。当在含有1.0 mM乙二醇双四乙酸（EGTA）的培养基中培养时，与在总钙浓度为0.007 mM的对照培养基相比，基础分泌显著降低。然而，外植体在含有EGTA的培养基中[3H]葡糖胺的总掺入量未改变，这表明培养基中低水平的钙选择性地损害了分泌过程。这些发现表明钙离子在胆囊糖蛋白分泌的调节中很重要。
