What causes the movement of calcium and sodium ions in and out of cardiac cells?

Alcium is removed from cells by two basic mechanisms.  The first mechanism involves an ATP-dependent Ca++ pump that actively removes calcium from the cell (see figure at right).  The second mechanism is the sodium-calcium exchanger.  The exact mechanism by which this exchanger works is unclear.  It is known that calcium and sodium can move in either direction across the sarcolemma. 

In the air and in the lower fre ah water