Long-term high potassium makes a kidney channel more active, and blocking that channel with a drug lowers blood pressure in mice.

Even though high potassium lowers a kidney transporter in mice, this doesn't explain the blood pressure changes, suggesting other mechanisms are at play.

When mice eat a lot of salt, adding a moderate amount of potassium lowers their blood pressure, showing that potassium's main benefit might be fighting high blood pressure caused by salt.

For a few days, extra potassium lowers mice's blood pressure, but after three weeks, it starts to raise it again.

When mice eat a lot of potassium for three weeks, their blood pressure goes up mostly at night, no matter how much salt they eat or what form of potassium they consume.

When mice don't get enough potassium, their kidney transporter becomes more active and blood pressure rises, but a common blood pressure drug can lower it again.