蛋白激酶C
二酰甘油激酶
内科学
内分泌学
胰岛素
血管平滑肌
甘油二酯
生物
油酸
孵化
磷酸化
生物化学
医学
酶
平滑肌
作者
Toyoshi Inoguchi,Pu Xia,Makoto Kunisaki,Seigo Higashi,Edward P. Feener,George L. King
出处
期刊:American Journal of Physiology-endocrinology and Metabolism
[American Physiological Society]
日期:1994-09-01
卷期号:267 (3): E369-E379
被引量:100
标识
DOI:10.1152/ajpendo.1994.267.3.e369
摘要
We have reported that membranous protein kinase C (PKC) activities and total diacylglycerol (DAG) levels are increased in the heart and aorta of diabetic rats, which cannot be easily reversed by euglycemic control. However, insulin treatment, which achieved euglycemia, can prevent the increase in PKC activities and DAG levels. Chronic exposure to elevated glucose levels (5.5 vs. 22 mM) increased DAG levels in cultured bovine and rat aortic endothelial cells and smooth muscle cells by 31, 140, and 143%, respectively, only after 3 days of incubation. Glyceraldehyde, which can stimulate the de novo synthesis of DAG, significantly increased DAG levels by 7.1 +/- 0.6-fold after only 16 h of incubation. Elevated glucose levels did not affect labeled DAG when all of the vascular cells were incubated with [3H]arachidonate, [3H]glycerol, or [3H]phosphatidylcholine, whereas [3H]palmitate- and [3H]oleic acid-labeled DAG levels were significantly increased, indicating that the glucose-stimulated increase in DAG is derived partially from the de novo synthesis pathway. Immunoblotting studies showed increases only in PKC isoform beta II but not alpha in aortic smooth muscle cells. The phosphorylation level of MARCKS protein, an intracellular substrate of PKC, was also increased, consistent with the PKC activity increase. These findings showed that diabetic and hyperglycemia-induced increases in PKC activity and DAG levels in the heart and aorta are preventable by insulin treatment.
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