Angiotensin II compartmentalization within the kidney: effects of salt diet and blood pressure alterations.
OBJECTIVE
All components of the renin-angiotensin-aldosterone system are present within the kidney. Renin, renin receptor, angiotensinogen and angiotensin AT1 and AT2 receptor and aldosterone synthase messenger RNA and protein are present in close proximity to the renal vasculature and tubules. The interaction between the different components of the renin-angiotensin-aldosterone system determines the level of activity of this system and in turn may influence the regulation of blood pressure and renal sodium handling.


RESULTS
Angiotensin through the stimulation of its subtype AT2 receptor regulates sodium excretion, renin synthesis and secretion. Aldosterone synthase mRNA and protein are expressed in glomeruli, renal vasculature and tubules, and are regulated by angiotensin AT1 receptor, diabetes and salt. Although aldosterone is known to influence renal tubular channels with the subsequent enhancement of sodium reabsorption, it is not clear if the renally produced aldosterone also influences renal sodium handling or blood pressure regulation. In addition, angiotensin II influences kidney function and structure through the stimulation of renal inflammation. New data suggest that the renal AT1 receptor plays an important role in the determination of blood pressure levels, and this effect is unique and non-redundant in the actions of extrarenal AT1 receptors.


CONCLUSIONS
The finding of new functions and components of the renin-angiotensin-aldosterone system clearly adds new knowledge to our understanding of how angiotensin II influences the kidney and blood pressure.
Siragy
Helmy M
HM
Division of Endocrinology and Metabolism, Department of Medicine, University of Virginia Health System, Charlottesville, VA 22908-1409, USA. hms7a@virginia.edu
D000804:Angiotensin II / Q000502:physiology*; D001794:Blood Pressure / Q000502:physiology*; D006801:Humans; D007668:Kidney / Q000502:physiology*; D012084:Renin-Angiotensin System / Q000502:physiology*; D012982:Sodium, Dietary / Q000378:metabolism*
D012982:Sodium, Dietary; D000804:Angiotensin II