Angiotensin II (Ang II) and angiotensin (1-7) play significant roles in intracrine signaling, which refers to the action of hormones within the cells where they are produced, rather than being secreted into the bloodstream.

1. Angiotensin II (Ang II):

   • Sodium Retention and Blood Pressure Regulation: Ang II is a potent regulator of blood pressure and fluid balance. It stimulates sodium and bicarbonate reabsorption in kidney proximal tubule cells, promoting sodium retention and increasing blood pressure. This is a crucial physiological role in maintaining fluid and electrolyte balance.
   • Growth and Inflammation: Ang II has growth-promoting and pro-inflammatory properties. It can induce cellular proliferation and hypertrophy, contributing to tissue remodeling and inflammation, which are important in conditions like hypertension and heart disease.
   • Intracellular Calcium Regulation: Ang II can increase intracellular calcium levels, which is essential for various cellular functions, including muscle contraction and neurotransmitter release.

2. Angiotensin (1-7):

   • Counter-Regulatory Effects: Ang (1-7) generally opposes the actions of Ang II. It acts through the Mas receptor and has vasodilatory, anti-proliferative, and anti-inflammatory effects. This makes it a crucial component in balancing the effects of Ang II, particularly in cardiovascular regulation.
   • Cardioprotective Role: Ang (1-7) has been shown to have cardioprotective effects, reducing cardiac hypertrophy and fibrosis. It acts as an antagonist to the Ang II/AT1 receptor pathway, which is known to be harmful to the heart.
   • Diuresis and Natriuresis: Ang (1-7) promotes diuresis (increased urine production) and natriuresis (excretion of sodium in urine), which helps in reducing blood volume and pressure.

These peptides are part of the renin-angiotensin system (RAS), which plays a critical role in cardiovascular and renal physiology. The balance between Ang II and Ang (1-7) is essential for maintaining homeostasis and preventing pathological changes in tissues.

For more detailed information, you can refer to these sources:

• NCBI Article on Angiotensin II
• ScienceDirect Overview on Angiotensin II
• Exploration of Angiotensin-(1-7) and Mas Receptor