PDE9A deficiency does not prevent chronic-hypoxic pulmonary hypertension in mice

Area of Science:

• Cardiovascular Research
• Pulmonary Hypertension
• Molecular Pharmacology

Background:

• Pulmonary arterial hypertension (PAH) treatments target cyclic guanosine monophosphate (cGMP)-specific phosphodiesterases (PDEs).
• PDE9A has the highest affinity for cGMP among known PDEs and is expressed in cardiac and lung tissues.
• PDE9A deficiency previously showed protection against left ventricular pressure overload in mice.

Purpose of the Study:

• To investigate the role of PDE9A in right ventricular (RV) remodeling in a chronic-hypoxic pulmonary hypertension (CH-PH) mouse model.
• To determine if PDE9A deficiency enhances natriuretic peptide (NP)-dependent cGMP signaling and prevents RV changes in CH-PH.

Main Methods:

• Wild-type and PDE9A-deficient mice were exposed to CH-PH for 3 weeks.
• Measurements included RV pressure, hypertrophy, and levels of cGMP, PDE9A, PDE5A, and VASP phosphorylation in lung and RV tissues.
• Circulating ANP levels were also assessed.

Main Results:

• CH-PH increased RV pressure and hypertrophy in both wild-type and PDE9A-deficient mice.
• No significant increase in cGMP or VASP phosphorylation was observed in either group.
• Downstream cGMP effectors were not elevated in knockout mice, and RV remodeling was not attenuated.

Conclusions:

• PDE9A deficiency did not provide protection against RV pressure overload and remodeling in the CH-PH mouse model.
• These findings do not support a significant role for PDE9A in the pathophysiology of murine CH-PH.
• PDE9A may not be a primary therapeutic target for this specific model of pulmonary hypertension.