[Increased concentration of Na,K-pumps in skeletal muscles of patients with chronic obstructive lung disease. Significance of magnesium depletion and treatment with glucocorticoids].

Patients with COLD may develop Mg depletion due to inadequate nutrition or treatment with diuretics and beta 2-agonists. In 36 consecutive COLD patients skeletal muscle concentrations of Mg and K were reduced by 22% and 14%, respectively, compared to 23 age- and sex-matched controls (p < 0.001). Patients receiving diuretics showed a further reduction of muscle Mg (-31%) and K (-27%) compared to controls. The mean concentration of Na,K pumps was increased by 31% (p < 0.001), while a more pronounced increase (+61%) was seen in 12 intensive care patients receiving high dosages of glucocorticoids. Thus muscle concentrations of Mg and K are reduced in COLD patients and are associated with an upregulation of the Na,K-pump concentration. It is plausible that this upregulation may be caused by glucocorticoid treatment. The clinical benefits of glucocorticoids may therefore in part be due to an increased activity and capacity of the Na,K-pump and thereby in a possible enhancement of muscle force.