High-dose magnesium sulfate attenuates pulmonary oxygen toxicity.

BACKGROUND AND

METHODS

Rats rapidly develop respiratory distress when exposed to 100% oxygen and die within a few days. Autopsy of the lung shows severe histologic damage characteristic of the adult respiratory distress syndrome. The purpose of this study was to evaluate the effects of magnesium sulfate loading in a rat model of acute oxygen toxicity. Thirty-four rats were divided into three groups. Group 1 (n = 18) served as a control (no magnesium therapy), while group 2 (n = 8) and group 3 (n = 8) received varying amounts of magnesium sulfate. All animals were exposed to 100% oxygen for 96 hrs or until death. Lung damage was quantitated by measuring the lung injury score on histologic examination.

RESULTS

Administering magnesium sulfate in moderate doses at infrequent intervals to rats (group 2) resulted in less severe oxygen-induced lung damage than that which occurred in rats not receiving magnesium (control group). However, the difference was not statistically significant. Rats (group 3) given doses of magnesium sulfate in amount and frequency adequate to maintain a serum magnesium concentration recognized as therapeutic in eclampsia significantly reduced oxygen-induced lung damage.

CONCLUSION

High-dose magnesium sulfate therapy can reduce lung injury caused by acute oxygen toxicity in rats.