PCNA and pulmonary arterial hypertension: In addition, ISO can reduce the content of 5-hydroxytryptamine (5-HT) in PAH rats, increase the expression of Nrf2 protein in the lung tissue of PAH rats, activate the antioxidant system, enhance the activity of SOD in lung tissue of PAH rats, and inhibit NOX1, 5-HTT, p-c-src and Proliferating Cell Nuclear Antigen(PCNA) protein expression, and decrease MDA content.