What is the mechanism of action of digitalis?

The main mechanism of action of digitalis is on the sodium-potassium ATPase of the myocyte. It reversibly inhibits the ATPase resulting in increased intracellular sodium levels. The build-up of intracellular sodium leads to a shift of sodium extracellularly through another channel in exchange for calcium ions.

How does the drug ouabain work?

Ouabain inhibits the Na-K-ATPase membrane pump, resulting in an increase in intracellular sodium and calcium concentrations. Increased intracellular concentrations of calcium may promote activation of contractile proteins (e.g., actin, myosin).

What is digoxin and its mechanism of action?

Mechanism of action Digoxin binds to and inhibits the sodium/potassium-ATPase (sodium pump) within the plasma membrane of cardiac myocytes. This inhibition increases the intracellular sodium content which in turn increases the intracellular calcium content which leads to increased cardiac contractility.

What is the difference between digitalis and digoxin?

Digoxin, also called digitalis, helps an injured or weakened heart pump more efficiently. It strengthens the force of the heart muscle’s contractions, helps restore a normal, steady heart rhythm, and improves blood circulation. Digoxin is one of several medications used to treat the symptoms of heart failure.

Is digitalis an agonist or antagonist?

Digitalis is a cholinergic agonist, a chemical compound with properties like acetylcholine or the parasympathetic nervous system.

How does ouabain affect the heart?

Cardiac steroids (CSs), such as ouabain and digoxin, increase the force of contraction of heart muscle and are used in the clinic for the treatment of heart failure. Their negative chronotropic effect is further exploited for heart rate control in atrial arrhythmias.

How does ouabain increase contractility?

They exert a positive inotropic effect on cardiomyocytes by inhibiting the plasma membrane sodium pump (Na,K-ATPase), decreasing the Ca-extrusion by the sarcolemmal cardiac sodium/calcium exchanger (NCX) and increasing the intracellular Ca-concentration and Ca-release during subsequent contraction cycles.

What does ouabain do to the membrane potential?

The effect of ouabain on the resting membrane potential, therefore, was due to a change in the transmembrane potassium ion gradient. This, in turn, resulted from a decrease in intracellular potassium activity and, apparently, from an increased potassium activity at the cell surface.

What is the difference between digoxin and digitalis?

Why is digitalis used in heart failure?

Is digitalis sympathetic or parasympathetic?

The parasympathetic limb of the autonomic nervous system is most sensitive to these effects of digitalis, and its properties are significantly altered with therapeutic concentrations of the drug. These actions are particularly important in mediating the electrophysiologic effects of digitalis.