Changes in free cytosolic calcium and accumulation of inositol phosphates in isolated hepatocytes by [Leu]enkephalin.
Changes in free cytosolic calcium and accumulation of inositol phosphates in isolated hepatocytes by [Leu]enkephalin.
复制标题
[Leu]脑啡肽导致分离的肝细胞中游离胞质钙的变化和肌醇磷酸盐的积累。
DOI：
10.1042/bj2380537
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发表时间：
1986
期刊：
影响因子：
--
通讯作者：
M. Titheradge
中科院分区：
文献类型：
--
作者：
R. P. Leach;S. B. Shears;Christopher J. KIRKt;M. Titheradge
Isolated hepatocytes from fed rats were used to study the effects of the opioid peptide [Leu]enkephalin on intracellular free cytosolic Ca2+ ([Ca2+]i) and inositol phosphate production. By measuring the fluorescence of the intracellular Ca2+-selective indicator quin-2, [Leu]enkephalin was found to increase [Ca2+]i rapidly from a resting value of 0.219 microM to 0.55 microM. The magnitude of this response was comparable with that produced by maximally stimulating concentrations of either vasopressin (100 nM) or phenylephrine (10 microM). The opioid-peptide-mediated increase in [Ca2+]i showed a dose-dependency comparable with the activation of phosphorylase, but it preceded the increase in phosphorylase alpha activity. Addition of [Leu]enkephalin to hepatocytes prelabelled with myo-[2-3H(n)]inositol resulted in a significant stimulation of inositol phosphate production. At 10 min after hormone addition, there were increases in the concentrations of inositol mono-, bis- and tris-phosphate fractions of 12-, 9- and 14-fold respectively. No effect was apparent on the glycerophosphoinositol fraction. The effect of 10 microM-[Leu]enkephalin on inositol phosphate production was significantly greater than that obtained with 10 microM-phenylephrine, but marginally smaller than that induced by 100 nM-vasopressin. However, at these concentrations all three agonists gave a comparable increase in [Ca2+]i and activation of phosphorylase a. These data provide evidence for [Leu]enkephalin acting via a mechanism involving a mobilization of Ca2+ as a result of increased phosphatidylinositol turnover.
