Effect of cellular Ca2+ loading on alpha 1-agonist or protein kinase C activators-mediated stimulation of phosphorylase "a" in liver cells |
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Authors: | J M Saz C González-Manchón M S Ayuso R Parrilla |
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Institution: | Endocrine Physiology Unit, Centro de Investigaciones Biológicas, Madrid, Spain. |
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Abstract: | Long chain unsaturated fatty acids stimulate phosphorylase "a" activity in liver cells. Similar degree of activation was achieved by increasing cellular Ca2+ content or by treatment with agents other than oleate, like 1,2-diolein or phorbol esters, sharing in common their ability to activate protein kinase C. In Ca2+-loaded liver cells only phenylephrine was capable of inducing a further stimulation of phosphorylase "a" activity. It is concluded that: 1) The state of activation of protein kinase C may play a role in the hormonal control of liver glycogen metabolism; 2) alpha 1-agonist-mediated activation of phosphorylase "a" can occur by a mechanism which is not related to a Ca2+-dependent activation of protein kinase C. |
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