Tanshinone IIA attenuates hypoxic pulmonary hypertension via modulating KV currents

The voltage-gated K(+) (KV) channels play an essential role in the etiology of chronic hypoxic pulmonary hypertension (CH-PH).Tanshinone IIA (TIIA), a major active component of Salvia miltiorrhiza Bunge (S. miltiorrhiza), has many biological protective effects. In the present study, we investigated whether KV channels were responsible for the protective effect of TIIA on CH-PH. In acute hypoxia experiments, the IKV currents of pulmonary artery smooth muscle cells (PASMCs) isolated from healthy rats were determined in the absence or presence of TIIA (5 μg/ml or 25 μg/ml) or 4-AP (1 mM). In chronic hypoxia experiments, rats were challenged by intermittent hypoxia or sustained hypoxia exposure for 4 weeks with or without TIIA (10 mg/kg) treatment. Subsequently, the hemodynamic data and the pathomorphological changes of pulmonary arteries were gathered. The expressions of KV2.1 and KV1.5 in pulmonary arteries were tested by Western blotting and RT-PCR, respectively. PASMCs were detached from intermittent hypoxia or sustained hypoxia exposure rats to evaluate the IKV currents. Results showed that TIIA markedly recovered acute hypoxia-induced the down-regulation of IKV currents in PASMCs. Moreover, TIIA significantly restrained chronic intermittent hypoxia or sustained hypoxia-induced pulmonary artery wall remodeling, accompanied with modulating the expressions of KV2.1 and KV1.5, and reversing the down-regulation of IKV currents. TIIA is thus an attractive potential therapy for CH-PH.