why do some cells burst when exposed to ouabain? (a drug that is used to treat heart failure and affects the Na+/K+ ATPase)
The drug ouabain, which is used to treat heart failure, affects the Na+/K+ ATPase enzyme present in the cell membrane. This enzyme is responsible for maintaining the balance of sodium and potassium ions inside and outside the cell.
When cells are exposed to ouabain, it inhibits the Na+/K+ ATPase enzyme, leading to an imbalance in the concentrations of sodium and potassium ions. This disruption can have significant effects on the cell.
One important consequence is the disruption of the osmotic balance of the cell. Normally, the cell's interior has a higher concentration of potassium ions and a lower concentration of sodium ions compared to the extracellular environment. This concentration gradient helps maintain the osmotic equilibrium.
When the Na+/K+ ATPase is inhibited by ouabain, the sodium ions that are normally pumped out of the cell start accumulating inside, while potassium ions are not efficiently pumped in. As a result, there is an increase in the concentration of solutes inside the cell, causing an increase in osmotic pressure.
This increased osmotic pressure can lead to water influx into the cell through a process called osmosis. The excess water influx causes the cell to swell and eventually burst, a phenomenon known as cell lysis.
So, to summarize, cells exposed to ouabain burst due to the inhibition of the Na+/K+ ATPase enzyme, which disrupts the osmotic balance and leads to water influx, causing the cell to swell and rupture.