Effect of cellular Ca2+ loading on alpha 1-agonist or protein kinase C activators-mediated stimulation of phosphorylase "a" in liver cells.
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.
Saz
J M
JM
Endocrine Physiology Unit, Centro de Investigaciones Biológicas, Madrid, Spain.
González-Manchón
C
C
Ayuso
M S
MS
Parrilla
R
R
D000316:Adrenergic alpha-Agonists / Q000494:pharmacology*; D000818:Animals; D002118:Calcium / Q000494:pharmacology*; D004075:Diglycerides / Q000494:pharmacology; D004789:Enzyme Activation / Q000187:drug effects; D005231:Fatty Acids, Unsaturated / Q000494:pharmacology; D008099:Liver / Q000201:enzymology*; D008297:Male; D019301:Oleic Acid; D009829:Oleic Acids / Q000494:pharmacology; D010084:Oxidation-Reduction; D010656:Phenylephrine / Q000494:pharmacology; D010762:Phosphorylase a / Q000378:metabolism*; D006005:Phosphorylases / Q000378:metabolism*; D011493:Protein Kinase C / Q000378:metabolism*; D051381:Rats; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
D000316:Adrenergic alpha-Agonists; D004075:Diglycerides; D005231:Fatty Acids, Unsaturated; D009829:Oleic Acids; D010656:Phenylephrine; D019301:Oleic Acid; D010762:Phosphorylase a; D006005:Phosphorylases; D011493:Protein Kinase C; D013755:Tetradecanoylphorbol Acetate; D002118:Calcium; C013965:diolein