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Active and inactive renin in the adrenal
T Inagami1, K Mizuno, M Naruse
1Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee 37232.
American Journal of Hypertension
|April 1, 1989
Summary
The adrenal gland synthesizes and stores renin in secretory granules. Its release is regulated and differs from kidney renin secretion, suggesting a unique role in adrenal function.
Area of Science:
- Endocrinology
- Renal Physiology
- Cell Biology
Background:
- Renin, an enzyme crucial for blood pressure regulation, is primarily known to be produced in the kidneys.
- Recent studies have indicated the presence of renin in adrenal glands across species, including humans, rats, and mice.
- The specific role and regulation of adrenal renin remain less understood compared to its renal counterpart.
Purpose of the Study:
- To investigate the synthesis, storage, and secretion of renin within the adrenal gland.
- To elucidate the subcellular localization and regulation mechanisms of adrenal renin.
- To compare the secretory control of adrenal renin with that of kidney renin.
Main Methods:
- Percoll density gradient centrifugation to determine subcellular distribution of adrenal renin.
- Immunohistochemistry and immunogold staining to identify renin in adrenal granules.
- Organ culture of adrenal capsules to assess renin release rates.
- Stimulation studies using potassium chloride, angiotensin II, and ACTH to investigate regulatory pathways.
Main Results:
- Adrenal renin is localized in dense secretory granules within the adrenal cortex.
- Bilateral nephrectomy significantly increases adrenal renin content and granule संख्या, suggesting regulation by kidney function.
- Adrenal renin secretion is stimulated by potassium chloride and angiotensin II, but not ACTH, indicating a distinct regulatory mechanism potentially involving intracellular calcium.
- Organ cultures demonstrate a regulated release of renin from adrenal capsules, with significantly higher secretion rates in nephrectomized rats.
Conclusions:
- The adrenal gland actively synthesizes renin, stores it in specific granules, and releases it in a regulated manner.
- Adrenal renin secretion is controlled by mechanisms distinct from the kidney, responding to hormonal and ionic cues.
- These findings highlight a novel role for the adrenal gland in the renin-angiotensin system, separate from renal renin production.