Related Experiment Videos
Renin is expressed in rat macrophage/monocyte cells
1First Department of Internal Medicine, Shiga University of Medical Sciences, Ohtsu-city, Japan.
Abstract:
The cardiac renin-angiotensin system has been suggested to be involved in various pathological conditions, including hypertrophy and remodeling. However, direct evidence that renin synthesized in situ is really involved in the putative angiotensin II generation is still lacking because of the relatively low abundance of renin mRNA in cardiac tissues. We evaluated renin mRNA expression levels in the ventricles under various pathological conditions and found that renin gene expression was markedly increased in the ventricles of isoproterenol-treated rats. Renin mRNA expression levels in the ventricles of rats that had been injected with isoproterenol (150 mg/kg SC) were transiently and markedly increased to 6-, 90-, and 4-fold compared with control expression levels at 24, 72, and 120 hours, respectively, after isoproterenol administration, Immunohistochemical analysis revealed that some of the OX-42-positive macrophage/monocyte cells had a reninlike immunoreactivity. An in vitro experiment indicated that rat peritoneal macrophage/monocyte cells expressed renin mRNA in abundance. The present study confirmed that a subpopulation of macrophage/monocyte cells could express renin. Macrophage/monocyte cells may be a source of tissue renin in some pathological conditions.
Insights
Cardiac renin gene expression increases significantly in pathological conditions. Macrophage/monocyte cells are identified as a potential source of this tissue renin, contributing to cardiac angiotensin II generation.
Area of Science:
- Cardiovascular Physiology
- Molecular Biology
- Immunology
Background:
- The cardiac renin-angiotensin system (RAS) is implicated in heart disease, but the source of cardiac renin remains unclear.
- Low renin messenger RNA (mRNA) levels in heart tissue limit understanding of its role in angiotensin II generation.
- This study investigates renin expression in cardiac tissue under pathological stress.
Purpose of the Study:
- To investigate renin gene expression in rat ventricles under pathological conditions.
- To identify the cellular source of renin in the heart.
- To explore the role of macrophage/monocyte cells in cardiac renin production.
Main Methods:
- Isoproterenol administration to induce cardiac pathology in rats.
- Quantitative analysis of renin mRNA expression in ventricular tissue.
- Immunohistochemical staining to identify renin-expressing cells.
- In vitro culture of rat peritoneal macrophage/monocyte cells to assess renin mRNA expression.
Main Results:
- Isoproterenol treatment caused a marked, transient increase in ventricular renin mRNA levels (up to 90-fold at 72 hours).
- Immunohistochemistry revealed renin-like immunoreactivity in OX-42-positive macrophage/monocyte cells.
- Rat peritoneal macrophage/monocyte cells expressed abundant renin mRNA in vitro.
Conclusions:
- Macrophage/monocyte cells express renin and may represent a significant source of cardiac renin.
- These cells could contribute to local angiotensin II generation in pathological cardiac conditions.
- This finding offers new insights into the cardiac renin-angiotensin system's role in disease.