AMPK activation is sufficient to increase skeletal muscle glucose uptake and glycogen synthesis but is not required for contraction-mediated increases in glucose metabolism.

The AMP-activated protein kinase (AMPK) is a cellular sensor of energetics and when activated in skeletal muscle during contraction can impart changes in skeletal muscle metabolism. Therapeutics that selectively activate AMPK have been developed to lower glucose levels through increased glucose disposal rates as an approach to abrogate the hyperglycemic state of diabetes; however, the metabolic fate of glucose following AMPK activation remains unclear. We have used a combination of in vivo evaluation of glucose homeostasis and ex vivo skeletal muscle incubation to systematically evaluate metabolism following pharmacological activation of AMPK with PF-739, comparing this with AMPK activation through sustained intermittent electrical stimulation of contraction. These methods to activate AMPK result in increased glucose uptake but divergent metabolism of glucose: pharmacological activation results in increased glycogen accumulation while contraction-induced glucose uptake results in increased lactate formation and glucose oxidation. These results provide additional evidence to support a role for AMPK in control of skeletal muscle metabolism and additional insight into the potential for AMPK stimulation with small molecule direct activators.

Relational energy at work: Implications for job engagement and job performance.

Energy is emerging as a topic of importance to organizations, yet we have little understanding of how energy can be useful at an interpersonal level toward achieving workplace goals. We present the results of 4 studies aimed at developing, validating, and testing the relational energy construct. In Study 1, we report qualitative insights from 64 individuals about the experience and functioning of relational energy in the workplace. Study 2 draws from 3 employee samples to conduct exploratory and confirmatory factor analyses on a measure of relational energy, differentiating relational energy from related constructs. To test the predictive validity of the new relational energy scale, Study 3 comprises data from employees rating the level of relational energy they experienced during interactions with their leaders in a health services context. Results showed that relational energy employees experienced with their leaders at Time 1 predicted job engagement at Time 2 (1 month later), while controlling for the competing construct of perceived social support. Study 4 shows further differentiation of relational energy from leader-member exchange (LMX), replicates the positive relationship between relational energy (Time 1) and job engagement (Time 2), and shows that relational energy is positively associated with employee job performance (Time 3) through the mechanism of job engagement. We discuss the theoretical implications of our findings and highlight areas for future research.