Question

Predict how BOTH the ability to generate an action potential AND the shape of the action potential might change under the following conditions. Explain your answers.

-Decrease in extracellular K⁺ concentration

-Increase in number of Na⁺ leak channels

-Blocking of Na⁺/K⁺ATPase with ouabain

-Decrease in extracellular Na+ concentration

Answer 1

Answer- Lower potassium levels in the extracellular space will cause hyperpolarization of the resting membrane potential. As a result, a greater than normal stimulus is required for depolarization of the membrane in order to initiate an action potential.

Answer- Ouabain is a cardiac glycoside that inhibiting the Na⁺/K⁺-ATPase sodium-potassium ion pump.Once ouabain binds to this enzyme, the enzyme ceases to function, leading to an increase of intracellular sodium which reduces the activity of the sodium-calcium exchanger (NCX), which pumps one calcium ion out of the cell and three sodium ions into the cell down their concentration gradient. Therefore, the decrease in the concentration gradient of sodium into the cell which occurs when the Na/K-ATPase is inhibited reduces the ability of the NCX to function. This in turn elevates intracellular calcium. This results in higher cardiac contractility and an increase in cardiac vagal tone

Answer- If extracellular Na+ concenteration gets decrease then membrane potential become more negative.