Figure 2.
TP receptor-specific GTPase activity is increased in hypoxic pulmonary artery myocytes. Neonatal pulmonary artery myocytes grown in hypoxia or normoxia, challenged for 2 min with TP receptor agonist 10−6 M U46619, with or without TP receptor blockade by 10−5 M SQ29546, then flash-frozen. GTPase activity quantified in membrane fractions. Organic Pi liberated by membrane GTPase from substrate GTP in response to U46619 was calculated from a standard curve as [Pi] min−1·mg−1 protein, after subtraction of baseline (unstimulated) Pi release. Measured GTPase activity represents Pi release specifically due to TP-G-protein complex GTPase activity. This activity is sensitive to TP receptor blockade (+SQ) (data from three separate experiments in triplicate). *P < 0.05.