ABSTRACT
Magnesium sulfate (MgSO4) infusion often lowers blood pressure, but the responsible mechanisms are not clear. Since catecholamines play a major role in blood pressure regulation, we studied the effects of MgSO4 infusion on blood pressure, pulse rate, and plasma catecholamines in late pregnant and in nonpregnant New Zealand white rabbits. Pregnancy was associated with higher levels of dopamine (P < 0.01) and epi-nephrine (P < 0.001). MgSO4 treatment decreased mean arterial pressure (P < 0.001), increased pulse rate (P < 0.01), decreased dopamine (P < 0.01) and decreased epinephrine (P < 0.001). No significant effect on norepinephrine levels was noted, and there was no evidence that the effect of MgSO4 treatment was influenced by pregnancy. Further investigation is needed to clarify the role of catecholamines in mediating the effects of pregnancy and MgSO4 treatment on blood pressure regulation.
