AMPK deficiency in smooth muscles causes persistent pulmonary hypertension after birth and premature death

Abstract

We address a paradox, that AMPK may facilitate hypoxic pulmonary vasoconstriction and its deficiency precipitate pulmonary hypertension. Here we show that AMPK α1/α2 deficiency in smooth muscles promotes persistent pulmonary hypertension of the newborn. Accordingly, dual AMPK-α1/α2 deletion in smooth muscles causes premature death of mice after birth, associated with increased muscularization and remodeling throughout the pulmonary arterial tree, reduced alveolar numbers and alveolar membrane thickening, but with no edema. Spectral Doppler ultrasound indicates pulmonary hypertension and attenuated hypoxic pulmonary vasoconstriction. Age dependent right ventricular pressure elevation, dilation and reduced cardiac output was also evident. KV1.5 potassium currents of pulmonary arterial myocytes are markedly smaller under normoxia, which is known to facilitate pulmonary hypertension. Mitochondrial fragmentation and reactive oxygen species accumulation is also evident. Importantly, there is no evidence of systemic vasculopathy or hypertension in these mice. Moreover, hypoxic pulmonary vasoconstriction is attenuated by AMPK-α1 or AMPK α2 deletion without triggering pulmonary hypertension.