Question

DIGITALIS IS PRESCRIBED FOR HEART FAILURE. IT IS AN INOTROPIC DRUG TO STRENGTHEN THE CONTRACTION.. IT EFFECTS ONLY THE NA/K PUMP IN THE CARDIAC CELL. THE MECHANISM INVOLVES A NA/CA EXCHANGER DRIVEN BY THE NA GRADIENT. WHAT IS THE MECHANISM OF THE INOTROPIC EFFECT ?

Answer 1

MECHANISM OF THE INOTROPIC EFFECT

The Digoxin apply its positive inotropic activity initially by bounding to and impeding the Na/k ATPase in the cardiac cell membrane. Sodium/Potassium ATPase enzyme function as a pump for external transfer of the Na+ in order to inside transfer of K+.

Na/k ATPase comprise a receptor for the digitalis glycosides and also for intracellular Na+ and extracellular K+.The Digoxin's hindrance of the Na/k pump leads to an enhancement in the intracellular (Na).

Because of the existence of a Na/ca antiport, a progress in the intracellular Na+ also leads to an progress in the intracellular Ca2+.

This progress in the Ca2+ is absorbed into the sarcoplasmic reticulum and then delivered to the cytoplasm upon trigger by an action potential.This heavy release of the calcium from sarcoplasmic reticulum leads to a powerful force of contraction.

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