INCREASED CHOLESTEROL-ESTER FORMATION DURING FORCED CHOLESTEROL-SYNTHESIS IN RAT HEPATOCYTES
INCREASED CHOLESTEROL-ESTER FORMATION DURING FORCED CHOLESTEROL-SYNTHESIS IN RAT HEPATOCYTES
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DOI：
10.1111/j.1432-1033.1975.tb03933.x
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发表时间：
1975-01-01
期刊：
影响因子：
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通讯作者：
NILSSON, A
中科院分区：
文献类型：
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作者：
NILSSON, A
通过比较3 H2O和[14 C]甲羟戊酸掺入大鼠肝细胞悬液中的胆固醇，计算出加入甲羟戊酸可刺激胆固醇生物合成4-7倍。添加3.3-6.7 mM甲羟戊酸也导致酯化的新合成胆固醇比例增加5-6倍。通过与周围血浆脂蛋白交换进入细胞的放射性胆固醇的酯化也增加，表明胆固醇酯形成速率的真正增加，而不是新合成的胆固醇用于酯化的更有选择性的利用。放线菌酮没有消除胆固醇酯化的增加，表明它不需要增加胆固醇酯化酶的合成。相反，这些数据表明，胆固醇的供应量可能是一个重要的因素，调节大鼠肝脏中胆固醇酯的形成速率。向培养基中添加0.5 mM油酸并没有显着增加胆固醇酯化程度，而与1%白蛋白结合的2 mM油酸使新合成的胆固醇被酯化的比例增加了约70%。细胞分泌放射性胆固醇酯到培养基中。环己酰亚胺抑制这种分泌约80%，但不影响新合成的胆固醇转移到周围血浆脂蛋白的速率。
By comparing the incorporation of3H2O and [14C]mevalonate into cholesterol in suspensions of rat hepatocytes, it was calculated that the cholesterol biosynthesis could be stimulated 4–7‐fold by addition of mevalonate. The addition of 3.3–6.7 mM mevalonate also caused a 5–6‐fold increase in the proportion of newly synthesized cholesterol that was esterified. The esterification of radioactive cholesterol, entering the cells by exchange with surrounding plasma lipoproteins was also increased, indicating that a true increase in the rate of cholesterol ester formation rather than a more selective utilization of newly synthesized cholesterol for esterification, occurred. The increase in cholesterol esterification was not abolished by cycloheximide, indicating that it did not require an increased synthesis of cholesterol esterifying enzyme. Instead the data suggest that the supply of cholesterol to the esterifiable pool may be an important factor, regulating the rate of cholesterol ester formation in rat liver. The addition of 0.5 mM oleic acid to the medium did not increase the degree of cholesterol esterification significantly, whereas 2 mM oleic acid bound to 1% albumin increased the proportion of newly synthesized cholesterol that was esterified, by about 70%.The cells secreted radioactive cholesterol esters into the medium. Cycloheximide inhibited this secretion to about 80% but did not affect the rate at which newly synthesized cholesterol was transferred to surrounding plasma lipoproteins.