FIGURE 2.

Graphical summary of possible mechanisms that explain how AMPK activation is involved in hypoxic pulmonary vasoconstriction. Physiological hypoxia results in increases in the AMP/ATP ratio, ROS production, and in LKB1 activation to promote AMPK Thr 172 phosphorylation. AMPK activation increases Ca²⁺ levels in pulmonary VSMCs to promote constriction through, (1) inhibition of voltage-dependent K⁺ channels, (2) activation of voltage-operated Ca²⁺ channels, and (3) activation of Ca²⁺-sensing sarcoplasmic reticulum.