Membrane cholesterol alters gallbladder muscle contractility in prairie dogs.
Membrane cholesterol alters gallbladder muscle contractility in prairie dogs.
复制标题
膜胆固醇改变土拨鼠胆囊肌肉的收缩力。
DOI：
10.1152/ajpgi.1996.271.1.g56
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发表时间：
1996
期刊：
影响因子：
--
通讯作者：
Behar,J
中科院分区：
文献类型：
--
作者：
Yu,P;Chen,Q;Biancani,P;Behar,J
膜胆固醇和胆囊肌收缩力之间的因果关系，通过改变膜胆固醇磷脂的摩尔比，使用富含胆固醇或无胆固醇的脂质体。用胶原酶酶促分离饲喂常规或高胆固醇（1.2%）饮食的草原犬鼠的胆囊单肌细胞。用蔗糖梯度法纯化胆囊肌细胞膜。使用胆固醇氧化酶法测量胆固醇。磷脂含量测定采用G.R. Bartlett（J.Biol.Chem.234：466-468，1959）。实验结果表明：（1）高胆固醇饲养后，胆囊肌细胞膜胆固醇含量和胆固醇/磷脂摩尔比增加90%，八肽胆囊收缩素引起的收缩反应降低58%，（2）正常胆囊肌细胞与高胆固醇脂质体孵育2 h后，也出现类似的变化;当肌细胞与无胆固醇脂质体孵育2-6小时后，体内或体外诱导的变化被逆转。我们的结论是，胆囊肌可能会将多余的胆固醇进入其质膜时，暴露于富含胆固醇的环境，过量的膜胆固醇损害肌肉收缩性，这些变化似乎是可逆的。
The cause and effect relationship between membrane cholesterol and gallbladder muscle contractility was examined by altering membrane cholesterol to phospholipid mole ratio using cholesterol-rich or cholesterol-free liposomes. Gallbladder single muscle cells, from prairie dogs that were fed either a regular or high-cholesterol (1.2%) diet, were isolated enzymatically with collagenase. Plasma membranes of gallbladder muscle were purified in sucrose gradient. Cholesterol was measured using the cholesterol oxidase method. Phospholipids were measured with the method of G.R. Bartlett (J. Biol. Chem. 234: 466-468, 1959). The results of this experiment are 1) after high-cholesterol feeding, cholesterol contents and cholesterol/ phospholipid mole ratio in plasma membranes of gallbladder muscle increased 90%, and muscle cell contraction in response to cholecystokinin octapeptide decreased 58%; 2) similar changes were observed when normal gallbladder muscle cells were incubated with cholesterol-rich liposomes for 2 h; and 3) the changes induced either in vivo or in vitro were reversed when muscle cells were subsequently incubated with cholesterol-free liposomes for 2-6 h. We conclude that gallbladder muscle may incorporate excess cholesterol into its plasma membrane when exposed to a cholesterol-rich environment, that excess membrane cholesterol impairs muscle contractility, and that these changes appear to be reversible.