Angiotensin as a renal growth promoting factor

Area of Science:

• Nephrology
• Endocrinology
• Molecular Biology

Background:

• The kidney's role in the systemic renin-angiotensin system (RAS) is well-established.
• Recent molecular characterization reveals a local RAS within the kidney, functioning independently of the systemic RAS.
• Specific cell populations along the nephron possess all necessary RAS components.

Purpose of the Study:

• To investigate the local intrarenal synthesis and growth-stimulating effects of angiotensin II (ANG II) on renal cells.
• To understand the role of the intrarenal RAS in kidney disease progression.

Main Methods:

• Molecular characterization of RAS components in renal cells.
• In vivo and in vitro studies using isolated perfused kidneys and cell cultures.
• Analysis of ANG II effects on cell proliferation, hypertrophy, transport, and metabolic pathways.

Main Results:

• Proximal tubular cells express all RAS components and produce high local concentrations of ANG II.
• ANG II influences glomerular hemodynamics, tubular transport, and metabolic processes like gluconeogenesis and ammoniagenesis.
• ANG II acts as a growth factor, inducing mesangial cell proliferation/hypertrophy and proximal tubular cell hypertrophy, which precede glomerulosclerosis and fibrosis.

Conclusions:

• The kidney possesses a functional local RAS with significant intrarenal production of ANG II.
• Intrarenal ANG II plays a critical role in regulating kidney function and acting as a growth factor for renal cells.
• Targeting the intrarenal RAS offers potential therapeutic strategies for preventing progressive kidney disease.