**Local Renin-Angiotensin System at Liver and Crosstalk with Hepatic Diseases**

Eylem Taskin and Celal Guven

Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/65919

### **Abstract**

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The systemic renin-angiotensin system mainly regulates blood pressure and maintains kidney function. Recent studies have realized that renin-angiotensin system (RAS) has been found in many tissues, such as heart, liver, and kidney. Although RAS in heart and kidney has been well documented, the RAS in the liver has been evaluated in a few studies. Therefore, this chapter will be assessed it. Based on findings, RAS in the liver has presented almost all of its components, such as angiotensin-I (Ang-I), angiotensin-II (Ang-II), angiotensin-converting enzyme (ACE), angiotensin type-1 receptor (AT1), angiotensin type-2 receptor (AT2), named as classical RAS. Expect these components, the local RAS has had alternative pathway components, including angiotensin-converting enzyme 2 (ACE2) and chymase. Classical RAS has an opposite effect of alternative RAS. Although these local RAS might not be such a crucial for the tissue, it could be a more vital function under pathophysiologic conditions. The chapter the local RAS in the liver the under both physiologic and pathophysiologic conditions is highlighted.

**Keywords:** angiotensin-II, angiotensin-converting enzyme 2, local renin-angiotensin system, liver pathologies

### **1. Introduction**

Although early studies focused on the systemic renin-angiotensin system (RAS) which are important endocrine cascade to regulate the salt-water balance, scientists have recognized there is one more RAS, called as local or tissue RAS except for classical systemic effects [1]. The first recognition of local RAS has been reported that the in dog's brain the renin was found [2]. Then, various tissues, such as the heart, liver, kidney, vasculature, skeletal muscles, pancreas, retina, adipose, neuronal, and reproductive tissue, have been shown to present local RAS [2–6]. Though systemic RAS can have a role in the regulation of cardiovascular homeo-

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stasis, there is accumulating evidence to suggest that the local RAS may affect tissue angiogenesis, proliferation, cell growth, apoptosis, tissue inflammation, differentiation, hormonal secretion, fibrosis and/or dependent of systemic RAS. The local RAS has the paracrine effect in the tissue. Indeed, it does not have to come along with the systemic RAS [2, 5].

The liver is critical organ to maintain not only to glucose homeostasis [7] but also almost all of the body's metabolic activities. The liver tissue has a great regeneration capacity against to repair of liver injury also [8]. The organ has reported existing both of systemic and local RAS [7]. The chapter could, therefore, focus on the local RAS in liver. However, there are limited studies available to study on local RAS. So, the aim of the present chapter is to analyze and sum up the participation of local RAS on both physiology and pathophysiology of liver tissue.
