A neuron is poisoned with the chemical ouabain which is an i

A neuron is poisoned with the chemical, ouabain, which is an inhibitor of the Na+ - K+ ATPase. Explain what would happen to the resting membrane potential (RMP) of the cell (will it depolarize, hyperpolarize or remain the same). In your answer, 1 identify the three factors that determine RMP in a neuron, 2 identify whether each factor causes membrane potential to be more or less negative, and 3 explain whether or not ouabain would affect each factor.

Solution

2) 1. High difference in ion concentration of intra and extracellular content would lead to high RMP

2. The greater the permeability of cells the higher the RMP

3. The activity of electrogenic pumps affect the RMP with increase in the Na⁺/K⁺-ATPase and Ca⁺⁺ transport pumps thus the RMP increases.

3) 1. ouabain decreses the intracellular ion concentration initially but due to no effect on extracellular ion conentration the RMP initally increases and later goes down to zero.

2. ouabain increases membrane permeability which initally shows increase in RMP but latter dissipate to the zero level

3. ouabain inhinibts the Na⁺/K⁺-ATPase and Ca⁺⁺ transport pumps thus prolonged inhibition of the Na⁺/K⁺ ATPase leads to a gradual dissipation of transmembrane Na⁺ and K⁺ concentration gradients and, thus, a gradual decline of the membrane potential until its value reaches zero