When mice eat a lot of salt, their kidney's salt-handling channels (NCC and ENaC) are already low, and adding more potassium doesn't make ENaC any higher.

When mice eat more potassium on normal salt, their kidney's salt-handling channels change: one type (NCC) slows down but another (ENaC) speeds up, especially when aldosterone hits about 2701 pg/24h.

In mice eating normal salt, even though extra potassium slows down one salt-handling channel (NCC), it doesn't lower blood pressure because another channel (ENaC) starts pulling in more salt instead.

When mice eat a lot of salt, adding a moderate amount of potassium lowers their blood pressure by about 3.6 mmHg compared to eating the same high salt without extra potassium.

In mice eating normal salt, too much potassium (over 1.75% of their diet) makes their blood pressure go up during active hours, especially at high potassium levels like 5%, because of increased activity of certain kidney channels.