The extent of hypertrophy was determined by quantitative real-time PCR (qRT-PCR) for 5 hypertrophy markers: Nppa, Nppb, Myh7, Acta1, and Pln. Although the hypertrophied hearts had similar appearances, the expression levels of the markers significantly differed between the PHH and PAH mice. Here, NPPB is linked to pulmonary arterial hypertension.