Fig. 1.

Capsaicin-induced increase in [Ca²⁺]_cyt is significantly enhanced in pulmonary artery smooth muscle cells (PASMCs) from patients with idiopathic pulmonary arterial hypertension (IPAH). A: representative traces showing changes in [Ca²⁺]_cyt in normal (top) and IPAH (bottom) PASMCs before and during extracellular application of 1, 10, 50, 100, and 500 μM capsaicin. B: representative traces showing changes in [Ca²⁺]_cyt in IPAH PASMCs in response to 50 μM capsaicin in the absence (control) or presence of 100, 300, and 1,000 nM 5′-iodoresiniferatoxin (5′-IRTX) (top) and 1, 10, 40 μM capsazepine (CPZ), the potent antagonists of TRPV1 channels (bottom). C: summarized data (means ± SE) showing the actual (top) and normalized (bottom) dose-response curves of capsaicin-induced increases in [Ca²⁺]_cyt in normal (white circles) and IPAH (black squares) PASMCs (n = 120–150 cells, 3–5 separate experiments). D: summarized data (means ± SE) showing the actual (top) and normalized (bottom) dose-response curves of 5′-IRTX-induced (left) and CPZ-induced (right) inhibition of increases in [Ca²⁺]_cyt in IPAH PASMCs induced by 50 μM capsaicin (n = 90 to 120 cells, 3 separate experiments). E: representative images (top) and summarized data (means ± SE, bottom) showing Western blot analysis of TRPV1 in PASMCs from three normal donor subjects (n = 3) and six patients with IPAH (n = 6). F and G: regular (F) and real-time (G) RT-PCR analyses of TRPV1 in PASMCs from three normal donor subjects (n = 3) and six patients with IPAH (n = 6). *P < 0.05 and ***P < 0.001 compared with normal PASMCs.