6.8 R-A System
The renin-angiotensin system (RAS), also known as the renin-angiotensin-aldosterone system, is an endocrine system that plays important roles in the regulation of blood pressure and fluid balance. The RAS shows aberration in patients with type 2 diabetes. In proliferative diabetic retinopathy (PDR), expression of the receptors and signaling molecules of the RAS are increased in the retina. These are, namely, renin, angiotensin converting enzymes (ACE) 1 and 2, and angiotensin receptors. These changes are seen to be independent of systemic blood pressure.