Effect of high K+ exposure on phosphoinositide metabolism in frog skeletal muscle. |
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Authors: | Z Dong K Y Chen P H Zhu |
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Institution: | Shanghai Institute of Physiology, Chinese Academy of Sciences. |
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Abstract: | Using 3H]myo-inositol labeled frog skeletal muscles, we have studied the effect of high K+ exposure on phosphoinositide metabolism. After 12 hours labeling, 80mM K+ exposure induced a time-dependent change. The labeling associated with phosphatidylinositol (PI) and phosphatidylinositol 4-phosphate (PIP) gradually increased and decreased, respectively. The labeled phosphatidylinositol 4,5-bisphosphate (PIP2) first decreased, and then recovered. An accumulation of the labeling in inositol phosphates was shown. In shortening the labeling to 30 min, 15 min high K+ exposure was found to only increase the labeling in all fractions. Taken together, these results show that high K+ exposure can activate the turnover of phosphoinositides, which is consistent with the hypothesis that the metabolism of phosphoinositides may regulate excitation- contraction (e-c) coupling. |
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