Magnesium attenuates the neutrophil respiratory burst in adult asthmatic patients.
BACKGROUND
IV magnesium (Mg2+) has been proposed as an emergent treatment for acute asthma exacerbations. Recent studies have focused on the effects of Mg2+ on bronchial smooth muscle, yet asthma is primarily an inflammatory disease.


OBJECTIVE
To assess the effects of Mg2+ on the neutrophil respiratory burst of adult patients with asthma.


METHODS
A prospective, blind study of volunteer adult asthmatic patients was performed. The patients' polymorphonuclear neutrophils (PMNs) were isolated, purified, and placed into phosphate-buffered saline with the following test conditions: concentrations of magnesium chloride (MgCl2) added: 0 mmol MgCl2, 1 mmol MgCl2 (low), and 10 mmol MgCl2 (high) both with and without the calcium (Ca2+) ionophore A23187 (0.1 mmol). PMNs were activated using N-formyl-methionyl-leucyl-phenylalanine (fMLP) (10 mumol), and the production of superoxide (O2-) was measured by the spectrophotometric reduction of cytochrome c.


RESULTS
Mg2+ reduced activated PMN O2- production compared with that for no Mg2+ (1.0 +/- 0.1 nmol O2-/5 x 10(5) PMN/min) in both low (-0.52* +/- 0.3 nmol O2-/5 x 10(5) PMN/min) and high (-0.76* +/- 0.3 nmol O2-/5 x 10(5) PMN/min; *p < 0.05) concentrations. The addition of A23187 increased O2- production in both the high (0.53* +/- 0.02 nmol O2-/5 x 10(5) PMN/min) and the low (1.5* +/- 0.6 nmol O2-/5 x 10(5) x 10(5) PMN/min) Mg2+ groups, with no change in the control group (1.2 +/- 0.2 nmol O2-/10(5) PMN/min).


CONCLUSIONS
In clinically relevant concentrations, Mg2+ attenuates the neutrophil respiratory burst in adult asthmatic patients. Mg2+ appears to affect PMNs by interfering with extracellular Ca2+ influx. Mg2+ may have a beneficial anti-inflammatory effect in asthmatic individuals.
Cairns
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CB
Division of Emergency Medicine, University of Colorado Health Sciences Center, Denver 80262, USA. charles.cairns@uchsc.edu
Kraft
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D000208:Acute Disease; D000328:Adult; D001249:Asthma / Q000188:drug therapy* / Q000276:immunology; D000001:Calcimycin / Q000627:therapeutic use; D015220:Calcium Channels / Q000187:drug effects; D004311:Double-Blind Method; D004359:Drug Therapy, Combination; D005260:Female; D006801:Humans; D007249:Inflammation; D007476:Ionophores / Q000627:therapeutic use; D015636:Magnesium Chloride / Q000494:pharmacology / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D016897:Respiratory Burst / Q000187:drug effects*
D015220:Calcium Channels; D007476:Ionophores; D015636:Magnesium Chloride; D000001:Calcimycin