A neurotransmitter that selectively opens potassium channels will alow potassium to move into the cell

Chloride ions and potassium ions move into the cell to hyperpolarise the cell

A neurotransmitter agent selectively opens ligand-gated chloride channels is the basis for an inhibitory postsynaptic potential

The Nernst potential for chloride is about -70mV, therefore chloride ions tend to move out of the cell along its electrochemical gradient

An increase in the extracellular sodium concentration leads to an inhibitory postsynaptic potential