Background
Insulin is known to act as second effector that provides potassium transfer from extracellular fluid to intracellular fluid, thus causing hypokalemia and arrythmia.
We evaluated the effect of magnesium sulfate treatment on hemodynamics and serum potassium concentration, induced by continuous infusion of regular insulin solution in rabbits.
Method
Twenty-four rabbits were divided into four groups for the experiment. Group I was given intravenouse injection of 5 ml of normal saline and continuous dripping of 7.5 U of RI. Group II was pretreated with 30 mg/kg of magnesium sulfate, followed by continuous dripping of 7.5 U of RI.
Group III was given 5 ml of normal saline and 15 U of RI.
And Group IV was administered 15 U of RI after 30 mg/kg of magnesium sulfate pretreatment.
Venouse blood sampling was done before pretreatment, and after 5, 30, 60 and 120 minutes respectively. Heart rate and arterial blood pressure were taken at the same intervals.
Result
1) There was no significant change in serum potassium concentration in groups injected with 7.5 units of RI respectively (groups I and II), regardless of magnesium pretreatment. But in groups injected with 15 units of RI, the group that was not pretreated with magnesium (Groups III) showed a decrease in serum potassium concentration from 3.39+/-0.57 Eq/L to 2.29+/-0.71 mEq/L, while the concentration in the pretreated group (Group IV) decreased more significantly from 3.35+/-0.50 mEq/L to 1.81+/-0.41 mEq/L.
2) Pulse rate did not change significantly in groups that received continuous infusion of 7.5 units of RI (groups I and II) regardless of magnesium pretreatment, but increased significantly in groups injected with 15 units of RI (groups III and IV), pretreated or not. The pretreated group (group IV) had a more significant rise in pulse rate compared with the group that was not pretreated (group III).
3) In all of the groups, those pretreated with magnesium (groups II and IV) and those not pretreated (groups I and III), there was no significant change in systolic and diastolic blood pressures. Nor was arrhythmia detected.
Conclusion
The above results indicate that while magnesium sulfate pretreatment at 30 mg/kg with insulin infusion affects serum potassium concentration, has an antiarrhythmic effect, and may induce tachycardia, it does not have any significant effect on blood pressure. |
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