AVP and Myocardial fibrosis: It is worth to mention that in the case of the continuous action of stimulating factors, prolonged secretion of arginine vasopressin (AVP), via V1A receptors expressed on cardiac tissue, stimulates protein synthesis in myocytes and development of myocardial hypertrophy, decreases heart contractility, activates cardiac fibroblasts, thus promoting myocardial fibrosis (19).