Related Experiment Videos
No inhibitory effect of increased serum magnesium upon pressor response to infused calcium
1Department of Internal Medicine, Nagoyashi Kohseiin Geriatric Hospital, Japan.
Insights
Increased serum magnesium does not inhibit the blood pressure-raising effects of calcium. Calcium elevates blood pressure and total peripheral vascular resistance (TPVR) via vasoconstriction, while magnesium alone has no significant hemodynamic impact.
Area of Science:
- Cardiovascular Physiology
- Electrolyte Homeostasis
Background:
- The pressor effect of calcium is well-documented.
- The potential inhibitory role of magnesium on calcium-induced vasoconstriction requires elucidation.
Purpose of the Study:
- To investigate whether elevated serum magnesium levels attenuate the pressor response to infused calcium.
Main Methods:
- Ten subjects received intravenous infusions of magnesium, calcium, or a combination.
- Hemodynamic variables including intra-arterial blood pressure, heart rate, and cardiac output were monitored.
- Total peripheral vascular resistance (TPVR) was calculated.
Main Results:
- Magnesium infusion alone did not alter blood pressure, cardiac output, or TPVR.
- Calcium infusion increased blood pressure and TPVR without affecting cardiac output.
- Co-infusion of calcium and magnesium produced similar pressor effects to calcium alone.
Conclusions:
- Calcium administration elevates blood pressure and TPVR, likely through arterial smooth muscle contraction.
- Increased serum magnesium does not appear to induce arterial vasodilation or inhibit calcium's pressor effects.
Objective:
The purpose of this study was to determine whether the pressor effect of infused calcium is inhibited by increased serum magnesium.
Design:
Intravenous infusions of calcium, magnesium, and calcium+magnesium were performed in 10 subjects and the effect upon haemodynamic variables was investigated.
Methods:
Intra-arterial blood pressure and heart rate were recorded during i.v. infusions of magnesium, calcium and calcium+magnesium. Cardiac output and serum concentration of electrolytes were measured before and after the infusions. Total peripheral vascular resistance (TPVR) was calculated from: mean blood pressure/cardiac output.
Results:
Magnesium infusion increased serum magnesium, but did not change blood pressure, cardiac output or TPVR. Calcium infusion increased serum calcium and elevated both blood pressure and TPVR with no change in cardiac output. Calcium+magnesium infusion increased both serum magnesium and calcium, showing elevation of blood pressure and TPVR with no change in cardiac output. Changes in haemodynamic variables caused by the calcium+magnesium infusion were similar to those caused by the calcium infusion alone.
Conclusions:
These results suggest that increased serum calcium elevates blood pressure and TPVR through arterial vasoconstriction by arterial smooth muscle contraction, but increased serum magnesium does not induce arterial vasodilation.