Effects of Acute Bouts of Swimming Exercise on AMPKα2 Expression in Mouse Skeletal Muscle

The 5′-AMP-activated protein kinase (AMPK) is a multisubstrate serine/threonine protein kinase that is ubiquitously expressed and functions as an intracellular fuel sensor activated by depletion of high energy phosphate compounds. The a2 isoform is by far the most abundant in skeletal muscle, representing at least 66% of total AMPK activity. The purpose of this study was to determine the effects of the different exercise (swimming) durations on AMPKα2 gene and protein expression, and the relationships between the expression of AMPK and blood glucose and muscle glycogen. C57 mice were divided into three groups: a sedentary control group, a 90-minute swimming exercise group, and an exhaustive swimming exercise group. AMPKα2 gene and protein expression in the quadriceps muscle were measured separately by real-time quantitative PCR and Western immunoblot after the swimming exercise. Blood glucose and muscle glycogen were also measured at the same time. The results showed that 90-minute and exhaustive swimming exercise induced significant increases in skeletal muscle AMPKα2 gene and protein expression compared to in the control group, and AMPKα2 expression was higher after exhaustive swimming than after 90-minute swimming exercise. There was a significant negative correlation between AMPKα2 expression and blood glucose level. The high AMPKα2 gene and protein expression induced by exercise might be one of the reasons for blood glucose reduction, but not the key factor which regulates the degradation of muscle glycogen during swimming exercise.