Dexamethasone up-regulates skeletal muscle maximal Na , K pump activity by muscle group specific mechanisms in humans

Abstract

Dexamethasone, a widely clinically used glucocorticoid, increases human skeletal muscle Na+,K+ pump content, but the effects on maximal Na+,K+ pump activity and subunit specific mRNA are unknown. Ten healthy male subjects ingested dexamethasone for 5 days and the effects on Na+,K+ pump content, maximal activity and subunit specific mRNA level (α1, α2, β1, β2, β3) in deltoid and vastus lateralis muscle were investigated. Before treatment, maximal Na+,K+ pump activity, as well as α1, α2, β1 and β2 mRNA levels were higher (P < 0.05) in vastus lateralis than in deltoid. Dexamethasone treatment increased Na+,K+ pump maximal activity in vastus lateralis and deltoid by 14 ± 7% (P < 0.05) and 18 ± 6..