Whether mice get extra potassium for a few days or weeks, a key kidney transporter becomes less active.

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 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.

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