The interrelation of renin and iron binding capacity

Area of Science:

• Physiology
• Endocrinology
• Nutritional Science

Background:

• Hypoxia triggers increased serum angiotensinogen and erythropoietin (EP) in rats.
• Erythropoietin (EP) increases peak after packed cell volume (PCV) and serum renin rise.
• The stimulus for renin production during hypoxic red cell expansion is unclear.

Purpose of the Study:

• To investigate if decreased iron stores stimulate renin production in rats undergoing hypoxic red cell expansion.
• To explore the potential clinical relevance by comparing findings to early human pregnancy.

Main Methods:

• Rats were fed either a low-iron diet or an iron-supplemented diet.
• Animals were subjected to hypoxia (0.48 atm) for 1 to 10 days.
• Serum was analyzed for total iron-binding capacity (TIBC) and renin levels; some rats received iron supplementation during hypoxia.

Main Results:

• Low-iron diet rats showed increased TIBC, elevated serum renin, and a positive correlation between them.
• Normal iron diet rats had lower TIBC, lower serum renin, and no correlation.
• Iron supplementation in low-iron diet rats reduced both TIBC and serum renin.

Conclusions:

• Reduced iron stores appear to stimulate renin production in rats experiencing hypoxia-induced red cell expansion.
• Increased TIBC and renin observed in early pregnancy in women suggest a similar iron-related mechanism.
• Decreased iron stores may be a common factor linking renin increases in both experimental hypoxia and early human pregnancy.