The role of aquaporin in stress physiology: A review

The concept of water movement across cell membranes eventually lead to identification of water channels, known as ‘Aquaporins’. The transport function exerted by aquaporins (AQPs) is carried out efficiently by 13 distinct isoforms of AQPs in mammals. AQPs help in regulation of physiological functions of various organ systems and have a functional role in stress associated with various pathological conditions. This review summarises the involvement of AQPs in transport of ROS and oxidative stress regulation in various organ systems. AQP1, AQP4, AQP7 and AQP9 are the major AQPs in the cardiac tissues of various animals, playing vital role in the patho-physiology of congestive heart failure, myocardial oedema, myocardial ischemia and polymicrobial sepsis. In digestive system, AQP1, AQP3, AQP4, AQP7, AQP8, AQP10 and AQP11 are localised in gastro-intestinal tract, modulating patho-physiology of pseudomembranous colitis, bile induced diarrhoea, irritable bowel syndrome and intestinal ulcers. AQPs in enteric tissues are engaged in metabolism of H₂O₂, providing a protective mechanism against oxidative stress. AQP1, AQP2, AQP3, AQP4 and AQP11 are major renal AQPs involved in ureteral obstruction, nephrogenic diabetes insipidus and kidney injury. In respiratory system, AQP1, AQP2, AQP4 and AQP5 are expressed in various pathological circumstances like lung injury and pulmonary inflammation due to oxidative stress. Thus, the evidences regarding the role of AQPs in oxidative stress offer a foundation for comprehending the adaptive mechanisms to oxidative injury at cellular level, which helps in strategizing breeding programmes and serves as biomarkers for efficient diagnosis.