Question

For the secondary active transport which relies on Sodium pump( Ca, Glucose, Amino acid, H), what will they be influenced by deplorization state of potential membrane?

Answer 1

Secondary active transport maintain sodium gradient for transport molecules across plasma membrane; so electrochemical potential difference causes pumping ions (H⁺) in/out of the cell. The energy derived through this process is used as the energy source. The formation of H⁺ gradients is important in cellular respiration and moving glucose into cells. Also, calcium pumps use ATP as an energy source to move calcium similar to sodium. In depolarization, sodium channels open, result in more Na⁺ inside the cells. Na+/K+ ATPase pump is essential for the maintenance of Na⁺ and K⁺ concentrations across the membrane. In response to the depolarization, K⁺ channel opens, allow potassium ions to rapidly diffuse out of the cell. So, Repolarization occurs with close of sodium channel. Under anoxic conditions, depletion of ATP, or pump activity inhibited by cardiac glycosides such as digoxin, Na⁺ accumulates within the cell and decrease of intracellular K⁺ . This causes depolarization of the resting membrane potential. Also in case of case Chlorella virus infection, potassium ion release, with rapid depolarization of host membrane.