An important cause of pulmonary arterial hypertension (PAH) in children with congenital heart disease (CHD) is increased pulmonary blood flow (PBF). To gain a better understanding of the disease process, the changes in biochemical pathways and metabolism of pulmonary arterial smooth muscle cells (PASMCs) were studied using a unique surgical ovine model of increased pulmonary blood flow. PASMCs isolated from 4-week-old lambs with increased PBF (shunt) showed lower oxygen consumption rates and lower extracellular acidification rates linked to glutamine metabolism when compared to controls. Shunt and control PASMCs both exhibited a switch into the reverse tricarboxylic acid (TCA) cycle, while only shunt cells showed a decrease of glucose being transformed into Acetyl CoA to enter the forward TCA cycle. Shunt PASMCs also demonstrated increased levels of yes-associated protein 1 (YAP1) expression in the nucleus. These results indicate changes in glutamine metabolism, glucose metabolism, and protein signaling cascades associated with increased mechanical forces in the setting of increased PBF, as seen in PAH in children with CHD.