Na/Ca exchanger moves calcium in relation to sodium at what ratio and direction?

Na/Ca exchanger moves calcium in relation to sodium at what ratio and direction?

• A. 1 Ca++ per 2 Na+ in
• B. 1 Ca++ per 3 Na+ in
• C. 2 Ca++ per 3 Na+ in
• D. 1 Ca++ per 4 Na+ in

Answer: (B)

The Na/Ca exchanger uses the inward gradient of Na+ to drive extrusion of Ca2+. Its typical stoichiometry is 3 Na+ for 1 Ca2+. In the forward mode, 3 Na+ enter the cell while 1 Ca2+ leaves the cell, so calcium moves in the opposite direction to sodium. Therefore, for every 3 Na+ transported, 1 Ca2+ is exchanged and moved outward. The idea captured by the option is the ratio of 1 Ca2+ for 3 Na+, emphasizing the 3:1 exchange, with the key point being that the calcium movement is opposite to the sodium movement.

The Na/Ca exchanger uses the inward gradient of Na+ to drive extrusion of Ca2+. Its typical stoichiometry is 3 Na+ for 1 Ca2+. In the forward mode, 3 Na+ enter the cell while 1 Ca2+ leaves the cell, so calcium moves in the opposite direction to sodium. Therefore, for every 3 Na+ transported, 1 Ca2+ is exchanged and moved outward. The idea captured by the option is the ratio of 1 Ca2+ for 3 Na+, emphasizing the 3:1 exchange, with the key point being that the calcium movement is opposite to the sodium movement.