Magnesium sulfate's impact on muscle strength and calcium levels in pregnant uterine muscle

Magnesium sulfate (MgSO4) at a concentration of 5 mmol/L significantly reduces contractile response and increases in intracellular calcium concentration in human myometrial strips.

• MgSO4 decreased spontaneous contractions and those induced by oxytocin and potassium chloride in a time and concentration-dependent manner.
• After 20 minutes of exposure to 5 mmol/L MgSO4, changes in contractile response and intracellular calcium concentration elicited by oxytocin were significantly reduced.
• MgSO4 did not alter the relationship between intracellular calcium concentration and contractile force during responses to oxytocin or potassium chloride.
• At 10 mmol/L, MgSO4's effects are more consistent with mechanisms operating outside of the cell.
• The findings suggest that MgSO4 inhibits contractile activity through both extracellular and intracellular pathways.

Simplified