The role of glycine in hepatic ischemia-reperfusion injury

Glycine is a non-essential amino acid which is cheap, easily available and relatively non-toxic. It is composed of a single carbon attached to an amino and a carboxyl group, with a molecular weight of 75. It is involved in the production of bile, nucleic acids, porphyrins and creatine phosphate. It is part of the normal human diet and is used clinically, as an irrigant solution in urological and gynaecological procedures. Glycine has broad spectrum anti-inflammatory, cytoprotective and immunomodulatory properties whose therapeutic role has largely been un-investigated. Since the demonstration of its cytoprotective effect on hypoxic cultured renal tubule cells, further research has established its mechanism of anti-inflammatory action, which depends on stimulation of glycine sensitive chloride channel receptors on the cell membrane. The mechanism of non-specific cytoprotective effect which is present even in chloride and calcium free media is not clear. However glycine is currently being used experimentally, in human liver transplant recipients and has been shown to be beneficial in animal models of ischemia-reperfusion injury (IRI) in liver and several other organs. This review addresses the properties of glycine, its mechanism of action and its role in modulating IRI with special reference to the liver, with the aim of stimulating translational research into the potential role of glycine as a pharmaceutical agent.