sodium pump

Also from Answers.com... Asthma How to prevent and treat an asthma attack.

A mechanism for transporting sodium ions across cell membranes against an opposing concentration gradient.

An active mechanism by which sodium is transferred against a concentration gradient from the inside to the outside of cells. The sodium pump plays an important role in maintaining the resting potential of muscle fibres and nerve cells. Its operation depends on energy from ATP.

A biologic mechanism that uses metabolic energy stored in ATP to achieve active transport of sodium ions across a membrane, such as the cell membrane or the multicellular membranes that make up the walls of renal tubules.