Does ouabain bind to the sodium binding site?
Our results suggest that ouabain binds at two sites along the ion permeation pathway of the Na+/K+ ATPase. The external site (low apparent affinity) occupies the same region as previous structural findings. The high apparent affinity site is, however, slightly deeper toward the intracellular end of the protein.
What does ouabain do to cells?
Ouabain binds, with high affinity and specificity, to the extracellular domain of the α-subunit of Na,K-ATPase. The binding inhibits the enzyme’s function, thereby altering the transmembrane electrochemical potential of the cell.
How does ouabain affect 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.
How does ouabain cause cell death?
After 6 h of exposure, ouabain stimulates a series of anti-apoptotic actions in SH-SY5Y cells, including concentration-dependent phosphorylation of Erk1/2, Akt, and Bad. Nevertheless, at the same time this CTS also induces a series of events that inhibit retinoic acid-induced neuritogenesis and promote cell death.
What does ouabain do to ATPase?
It is concluded that ouabain stimulates proliferation in ADPKD cells by binding to the Na,K-ATPase with high affinity and via activation of the MEK-ERK pathway. The Na,K-ATPase is an enzyme of the plasma membrane of most cells that uses cellular ATP to exchange cytoplasmic Na+ for extracellular K+ (1).
What effect does ouabain have on the Na K pump?
In cardiac cells, ouabain increases intracellular Ca2+ concentration and cardiac muscle contractility by inhibiting Na-K-ATPase activity, thus stimulating Na/Ca exchange (4). In some cells, however, ouabain at very low (pM to nM) concentrations increases Na-K-ATPase activity (23).
How does ouabain affect the Na K pump?
Ouabain is a cardiac glycoside that inhibits ATP-dependent sodium-potassium exchange across cell membranes. The binding of ouabain to the sodium-potassium pump (also called Na+/K+ ATPase) prevents the conformational changes necessary for its proper function.
How does ouabain affect potassium?
How does ouabain inhibit sodium-potassium pump?
What effect would ouabain have on intracellular Na+ concentration?
Higher ouabain concentrations, which others have shown to clearly inhibit active Na and K transport, are shown to upset intracellular potassium activity homeostasis and to consistently produce toxicity.
How do you inhibit Na K-ATPase?
Since Na,K-ATPase is important for maintaining various cellular functions, its inhibition could result in diverse pathologic states. Inhibition of Na,K-ATPase causes high intracellular Na+ ion levels and subsequent increases in intracellular Ca2+ ion through the Na+/Ca2+ exchanger .
How does ouabain treat heart failure?
Cardiac steroids (CSs), such as ouabain and digoxin, increase the force of contraction of heart muscle and are used for the treatment of congestive heart failure (CHF). However, their small therapeutic window limits their use.
Where can I find Na+/K+ ATPase?
1 Department of Pharmacology, Medical University of Vienna, Waehringer Strasse 13A, 1090 Vienna, Austria. The Na (+)/K (+) ATPase is an almost ubiquitous integral membrane protein within the animal kingdom. It is also the selective target for cardiotonic derivatives, widely prescribed inhibitors for patients with heart failure.
Is Na+/K+ ATPase a target for cardiotonic derivatives?
The Na (+)/K (+) ATPase is an almost ubiquitous integral membrane protein within the animal kingdom. It is also the selective target for cardiotonic derivatives, widely prescribed inhibitors for patients with heart failure. Functional studies revealed that ouabain-sensitive residues distributed widely throughout the primary sequence of the protein.
What is Na+/K+ATPase?
The Na (+)/K (+) ATPase is an almost ubiquitous integral membrane protein within the animal kingdom. It is also the selective target for cardiotonic derivatives, widely prescribed inhibitors for patients with heart failure.