Because the thing about vascular tone,
Is not just more or less vasoconstriction,
When tone is reduced,
This is often produced,
By the active process of vasodilatation.

Phase 4 of Valsalva Manoeuvre,
Occurs when the breath hold’s released.
The increased venous return,
Stimulates the vagus in turn,
Causing the heart rate to decrease.

Ringers indeed contains potassium,
But its concentration is relatively low.
Its volume of distribution,
Means no increased concentration,
As study on study now show.

I used to have an excellent French phrase book full of helpful phrases such as this.

It was called C’est Pour Mon Crapaud (it’s for my toad)