**4.3 Role of angiotensin II, hypertension and hyperfiltration**

With progression of kidney disease the afferent arteriole tone decreases to a much larger extent than the efferent tone. As a result intra-glomerular pressure rises leading to hyperfiltration. Angiotensin II aides in hyperfiltration through its vasoconstrictor effect predominantly on the efferent arteriole. Apart from its hemodynamic effects, Angiotensin II acts directly on the glomerular membrane. It acts on the angiotensin II receptors on the surface of the podocytes, altering their permselective property, by contracting the foot processes. This allows proteins to escape in the urinary space.

Angiotensin II also induces proliferation ofglomerular cells and fibroblasts. It acts on AT1 receptors on tubular cells causing hypertrophy, which results in increased synthesis of collagen type IV. It increases macrophage activation and phagocytosis responsible for the inflammatory component associated with CKD.
