Magnesium in blood and tissues during cold acclimation

¹ Department of Physiology and Pharmacology, University of Missouri School of Medicine, Columbia, Missouri

Serum, heart, liver, and skeletal muscle Mg were determined on control and cold-exposed rats at 10-day intervals for 6 weeks. Serum Mg was also measured at 1- and 5-day periods. Deep colonic temperatures were measured at 1, 4, 12, 22, and 40 days and footpad temperatures at 1, 2, 3, 5, and 40 days of cold exposure. Heart and skeletal muscle Mg levels were elevated significantly at 10 days, serum Mg at 1, 5, 10, and 20 days, and deep colonic temperatures at 1, 12, and 22 days. The elevated Mg levels of heart and skeletal muscle suggest that the greater amount of serum Mg did not come from these tissues. The loss of liver Mg at 40 days of exposure remains obscure. Footpad temperature decreased from control throughout the acclimation period. The existence of peripheral hypothermia coupled with increased tissue Mg suggests hypothermic peripheral tissues such as skin as the most likely source of the transient rise of serum Mg during cold acclimation.