Human body is a collection of trillions of cells.  Life  is nothing but , a bundle of energy flowing across each of these cells  .Every  organ  has a  specailised mode of communication among themselves and others. When a cell is in an excited state , there is a  likelihood of spontaneous electrical activity.This can happen in nerve cells, cardiac cells , GI tract,  or virtually in  any cell  which has a porous cell membrane and ionic fluxes across it .

• Each cell membrane has a resting membrane potential . It  varies between -60 to – 90mv in most cells. When this potential increases there a propensity for  arrhythmias in heart  and convulsions in the brain , peristalsis in intestines and so on .
• Drugs  like local anesthetic lignociane acts by blocking the  Na+ channels and there by neural activation .Similarly magesium  acts on these channels to reduce the excitability of these cells.
• We know,  the sharp ascending stroke of cellular  action potential is mediated by Na + .Blockage of this channel blunts the action potential voltage and thus  the  early and late after depolarisation is prevented
• Magnesium sulphate’s anticonvulsant action is directly  attributable  to this membrane stabilising action

Thus , membrane stabilising action  can be termed as “membrane sedating”  action