Sodium Tanshinone IIA sulfonate (12.5 μM) inhibits hypoxia-induced PKG and PPAR-γ downregulation in PASMCs and distal pulmonary arteries of rats. The suppressive effects of Sodium Tanshinone IIA sulfonate on TRPC1 and TRPC6 expression in hypoxic PASMCs can be prevented by specific knockdown PKG or PPAR-γ. The suppressive effects of Sodium Tanshinone IIA sulfonate on basal calcium concentration and SOCE in hypoxic PASMCs can be reversed by specific knockdown of PKG or PPAR-γ. PKG-PPAR-γ signaling axis participates in the suppressive effects of Sodium Tanshinone IIA sulfonate on proliferation in hypoxic PASMCs. PPAR-γ agonist promotes the protective role of Sodium Tanshinone IIA sulfonate on basal [Ca]i and SOCE in hypoxic PASMCs. Sodium tanshinone IIA sulfonate inhibits the activity of CYP3A4 in a dose-dependent manner by the HLMs and CYP3A4 isoform. The KM and Vmax values of STS are 54.8±14.6 µM and 0.9±0.1 nmol/mg protein/min, respectively, for the HLMs and 7.5±1.4 µM and 6.8±0.3 nmol/nmol P450/min, respectively, for CYP3A4. CYP1A2, CYP2A6, CYP2C9, CYP2D6, CYP2E1, and CYP2C19 show minimal or no effects on the metabolism of STS. Sodium Tanshinone IIA sulfonate inhibits the activity of CYP3A4 in a dose-dependent manner in the HLMs and CYP3A4 isoform. Sodium Tanshinone IIA sulfonate primarily inhibits the activities of CYP3A4 in vitro, and Sodium Tanshinone IIA sulfonate has the potential to perpetrate drug-drug interactions with other CYP3A4 substrates.