Valinomycin is an Ionophores- i.e it makes the inner membrane permeable to compounds which are ordinarily unable to cross.
The amphipathic molecules dissolve in phospholipid bilayers of the mitochondria
It shields the electric charge as the ion passes through the membrane, providing a polar environment for the ion and a hydrophobic face to the other side. mobile carrier catalyzes the electrical movement of K+ across phospholipid bilayers. Hence Accumulation of potassium inside the mitochondria
This dissipates the essential transmembrane electrochemical gradients causing tremendous metabolic upheaval in the mitochondria.