Ion Channel Regulation by the LKB1-AMPK Signalling Pathway: The Key to Carotid Body Activation by Hypoxia and Metabolic Homeostasis at the Whole Body Level

Our recent investigations provide further support for the proposal that, consequent to inhibition of mitochondrial oxidative phosphorylation, activation of AMP-activated protein kinase (AMPK) mediates carotid body excitation by hypoxia. Consistent with the effects of hypoxia, intracellular dialysis from a patch pipette of an active (thiophosphorylated) recombinant AMPK heterotrimer (α2β2γ1) or application of the AMPK activators AICAR and A769662: (1) Inhibited BK _Ca currents and TASK K ⁺ currents in rat carotid body type I cells; (2) Inhibited whole-cell currents carried by KCa1.1 and TASK3, but not TASK1 channels expressed in HEK293 cells; (3) Triggered carotid body activation. Furthermore, preliminary data suggest that either conditional knockout of LKB1 in type I cells or global knockout of the catalytic α1 and α2 subunit of AMPK, respectively, markedly attenuated the ventilatory response of mice to hypoxia. Accumulating evidence therefore suggests that the LKB1-AMPK signalling pathway is necessary for hypoxia-response coupling by the carotid body, and serves to regulate oxygen and therefore energy supply at the whole body level.