The Study
The role of calcium ion as a mediator of the effects of angiotensin II, catecholamines, and vasopressin on the phosphorylation and activity of enzymes in isolated hepatocytes.
This study looked at how certain hormones affect tiny parts inside liver cells in a test tube. It shows a possible way they might work, but it doesn't prove this happens in people or causes any real health effects.
Analysis score
Maximum 58 for a case-control study.
Where the score came from
Two hormones, angiotensin II and vasopressin, tell the liver to make more sugar by changing how certain enzymes are tagged, without using the usual sugar-making signal. Glucagon does the same thing but uses a different signal.
Where does this study sit?
Reviews of RCTs (Meta-analyses)
Max 100Randomized Trials
Max 90Reviews of Cohort Studies
Max 85Cohort Studies
Max 72Reviews of Case-Control Studies
Max 63Case-Control Studies
Max 58Cross-Sectional & Case Series
Max 50Expert Opinion
Max 534 / 100
Quality score
Researchers compare people who have a condition (cases) with similar people who do not (controls), looking back in time for differences in exposure. Useful but more prone to bias.
Key takeaways
Summary
Based on the study abstract and findings.
- 1Yes — these changes mean the liver produces more glucose and stores less, which could raise blood sugar levels — important for understanding how stress or dehydration might trigger high blood sugar.
- 2Angiotensin II and vasopressin increased phosphorylase activity by 250–260%, decreased glycogen synthase activity by 50%, and decreased pyruvate kinase activity by 30–70%.
- 3These changes only happened when calcium was present.
Score breakdown, methodology, conflicts of interest, evidence analysis & raw study data
Publication
Journal
The Journal of biological chemistry
Year
1979
Authors
J. Garrison, M. Borland, V. Florio, D. A. Twible
Related Content
Claims (4)
Vasopressin increases the liver's production of glucose from non-sugar sources.
Glucagon triggers the addition of phosphate groups to 11 to 12 specific proteins inside liver cells by activating an enzyme that responds to cyclic AMP. Angiotensin II and vasopressin do not change cyclic AMP levels in these cells.
In liver cells, the hormones angiotensin II, vasopressin, and glucagon alter the phosphorylation state of three key enzymes—phosphorylase, glycogen synthase, and pyruvate kinase—and these modifications directly correspond to changes in the enzymes' activity levels.
Angiotensin II and vasopressin trigger the addition of phosphate groups to 10 to 12 proteins in liver cells, which correlates with a 250–260% rise in phosphorylase activity, a 50% drop in glycogen synthase activity, and a 30–70% drop in pyruvate kinase activity.
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.