Regulation of the sarcolemmal Na-K Pump by FXYD proteins [ 2006 - 2008 ]

Research Grant

Researchers: Prof Helge Rasmussen (Principal investigator) ,  A/Pr Francesca Marassi ,  A/Pr Ronald Clarke

Brief description Background. Pump molecules embedded in the membranes of all cells maintain a difference in composition between the cell content and the surrounding tissue fluids. Of these, the membrane sodium-potassium pump (Na+-K+ pump) is the most important. It uses metabolic energy generated in the cell to transport 3Na+ out in exchange for 2K+ transported in, and maintains a low concentration of Na+ and a high concentration of K+ within cells. The opposite applies to the surrounding tissue fluids. The concentration gradient for Na+ serves in mechanisms that couple transport of other ions and molecules to the downhill movement of Na+ in the direction determined by its concentration gradient. The transport of ions and molecules directly and indirectly due to the operation of the membrane Na+-K+ pump is very important for the function of all cells. Objectives. It is poorly understood how cells regulate the activity of their membrane Na+-K+ pumps. We will examine if small molecules (FXYD proteins) in the cell membrane, closely associated with the pump, regulate its activity. Methods. We will use a whole-cell patch clamping technique to attach small glass pipettes to single heart cells and replace their content with solutions in the pipettes. The technique allows real-time measurement of Na+-K+ pump activity because the 3:2 Na+:K+ exchange ratio generates an electrical current that can be measured in the single cells. The FXYD proteins will be produced in bacteria, purified and introduced into the heart cells by inclusion in the pipette solution that replace the cell content. Expected outcomes. Achieving this project's objectives will greatly enhance our understanding of Na+-K+ pump regulation. This is important because high levels of Na+ in heart cells is a pivotal abnormality in heart disease. Understanding the Na+-K+ pump can be activated to reduce cell Na+ levels should help design of treatments.

Funding Amount $AUD 268,264.67

Funding Scheme NHMRC Project Grants

Notes Standard Project Grant