Question

Why would cardiac glycosides (Na⁺/K⁺ ATP-ase inhibitors) be used to increase cardiac contractile force in a patient with heart failure?

Group of answer choices

Reducing the concentration gradient for Na⁺ would cause a larger depolarisation during an action potential, hence releasing more intracellular Ca²⁺ stores.

Reducing the concentration gradient for Na⁺ would inhibit the action of the Na⁺/Ca²⁺ exchanger, increasing intracellular Ca²⁺ concentrations.

Inhibiting this pump would lead to a reduction in the ATP requirements for the cell, allowing it to use the surplus ATP to increase contractile force.

The release of Ca²⁺ from the sarcoplasmic reticulum in cardiac myocytes is dependent on ryanodine receptors which open in response to increased ICF Na⁺ concentrations.

Answer 1