effect on central nervous system
- certain effects of Mg are similar to Ca.
- Increased concentration of Mg cause depression of CNS
- decreased concentration of Mg cause irritability of CNS
effect on neuromuscular system
- direct depressant effect on skeletal muscles - excess of Mg cause decrease in acetylcholine release by motor nerve impulse.
- the action of increased Mg on neuromuscular function are antagonized by Ca.
- abnormaly low concentration of Mg in extracellular fluid result in increased acetylcholine release and increased muscle excitability (tetany)ใ
- excess of Mg cause vasodilation.
hypomagnesemia cause
- changes in skeletal and cardiac muscle
- changes in neuromuscular function
- hyperirritability, psychotic behaviour
- tetany
hypermagnesemia cause
-muscle weakness
- hypotension
- ECG changes
- sedation and confusion
hypermagnesemia is usual due to renal insuficiency.