biochemistry - Why pouring salt in the wounds is painful?

De salt particles are alien bodies and can damage the tissue by mechanical means (This would also happen if you pour sand into an open wound). Also, the exposed tissue is vulnerable to dehydration, wich happens faster if the osmotic pressure is higher. Finally, nerve tissue is particulary sensible to changes in the ion composition of its sorroundings, so the added sodium may affect the action potential of the nociceptors.