Fig. 6.

Mechanisms of ET-1 action in the osteoblast. (A) ET-1 (100 nM) increased bone formation (orange staining between arrows) and was blocked by either atrasentan (10 µm) or DKK1 (50 ng/mL) in the calvarial organ culture assay. ET-1 reduced DKK1 secretion from calvaria that was restored with atrasentan. (B) ET-1 increased cell number, proliferation, and survival of calvarial osteoblasts. (C) DHT (10 nM), but not E₂ (10 nM), increased new bone formation (orange staining between arrows) and osteoblast number in the calvarial organ culture assay after 7 days of treatment. DKK1 production by calvaria was unchanged by sex steroids (*p ≤ 0.05).